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40 pages, 936 KB  
Review
Molecular and Structural Changes, and Skeletal Muscle Strength and Endurance in Chronic Obstructive Pulmonary Disease and Interstitial Lung Disease: Practical Applications of Assessment and Management
by Nina Patel and Ahmet Baydur
Bioengineering 2026, 13(3), 329; https://doi.org/10.3390/bioengineering13030329 - 12 Mar 2026
Viewed by 97
Abstract
Chronic obstructive pulmonary disease, interstitial lung disease, and post-lung trans-plantation are often accompanied by skeletal muscle dysfunction that worsens the quality of life. Such physiological changes are driven by physical inactivity, systemic inflammation, oxidative stress, anabolic and hormonal resistance, and medication effects. Structural [...] Read more.
Chronic obstructive pulmonary disease, interstitial lung disease, and post-lung trans-plantation are often accompanied by skeletal muscle dysfunction that worsens the quality of life. Such physiological changes are driven by physical inactivity, systemic inflammation, oxidative stress, anabolic and hormonal resistance, and medication effects. Structural changes include impaired capillarization, fiber-type shifts (slow-to-fast in limb muscle and fast-to-slow in respiratory muscles), mitochondrial dysfunction, reduced oxidative capacity, and early lactate accumulation. Electromyography and dynamometry, both isokinetic and isometric, quantify neuromuscular drive through measuring strength, power, and endurance and are associated with functional outcomes (6-min walk, sit-to-stand, stair climbing tests). Pulmonary rehabilitation (PR) improves neuromuscular efficiency, dyspnea, exercise tolerance, and quality of life by combining resistance, endurance, and eccentric training. The effects of PR generally plateau at three months, emphasizing the need for maintenance and the personalization of rehabilitation plans. While nutritional optimization is important, supplements have shown little benefit. Future priorities include defining EMG/dynamometry thresholds to allow standardized routine testing for comparable benchmarks and more precise PR protocols. Future research targeting mitochondrial remodeling, inflammatory signaling, and anabolic resistance offer potential pathways for preventing and reversing muscle wasting. Full article
(This article belongs to the Special Issue Musculoskeletal Function in Health and Disease)
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19 pages, 1538 KB  
Article
Mirror Visual Feedback Selectively Attenuates Crossover Fatigue in Distal Upper Limb Musculature: A Randomized Controlled Crossover Investigation Comparing Children and Adults
by Aymen Ben Othman, Wissem Dhahbi, Manel Bessifi, Vlad Adrian Geantă, Vasile Emil Ursu, David G. Behm, Karim Chamari and Anis Chaouachi
Life 2026, 16(3), 435; https://doi.org/10.3390/life16030435 - 8 Mar 2026
Viewed by 238
Abstract
This investigation examined whether mirror visual feedback modulates crossover fatigue magnitude during unilateral handgrip exertion and whether efficacy demonstrates age-dependent and muscle-group-specific characteristics. Thirty-three participants stratified by developmental stage (adults: n = 17, 24.64 ± 5.38 years; children: n = 16, 11.87 ± [...] Read more.
This investigation examined whether mirror visual feedback modulates crossover fatigue magnitude during unilateral handgrip exertion and whether efficacy demonstrates age-dependent and muscle-group-specific characteristics. Thirty-three participants stratified by developmental stage (adults: n = 17, 24.64 ± 5.38 years; children: n = 16, 11.87 ± 0.79 years) completed a randomized controlled crossover protocol incorporating three visual feedback conditions: mirror reflection of the exercised limb, occluded vision (no-mirror), and passive rest control. Participants performed unilateral dominant handgrip fatigue induction (20 × 6 s maximal voluntary isometric contractions) while bilateral force production was quantified pre-intervention and post-intervention across handgrip, elbow flexion, and elbow extension domains. Linear mixed-effects models with participant-specific random intercepts and slopes quantified Condition × Time × Limb interactions. In the non-exercised contralateral limb, linear mixed-effects models demonstrated that under the mirror condition, non-dominant handgrip force was maintained at rest-equivalent levels relative to control (+0.02 kg, 95% CI [−1.15, +1.17], p = 0.987, dz =+ 0.003), whereas vision occlusion induced significant crossover fatigue (−3.37 kg [−4.40, −2.35], p < 0.001, dz =− 1.16). All contrasts represent within-subject difference-of-differences in non-dominant limb change score (Post − Pre) extracted from the full factorial LMM via emmeans within the Limb = Non-dominant stratum pooled across age groups. The mirror versus no-mirror comparison yielded +3.38 kg [+2.43, +4.34], p < 0.001, dz =+ 1.26. Age-stratified analyses confirmed comparable effect magnitudes (adults: dz =+ 1.40; children: dz =+ 1.33). Muscle-group specificity emerged for handgrip but not elbow flexion (p = 0.068) or extension (p = 0.156). Age Group × Condition × Time × Limb interactions were non-significant (all p > 0.16), providing no evidence of age moderation within the tested developmental range. Mirror visual feedback constitutes an effective countermeasure against crossover fatigue in distal upper limb musculature. The magnitude of mirror-induced attenuation did not differ between children (aged 10–13 years) and adults within our sample, with no statistically detectable age moderation within the tested developmental range; formal equivalence testing was not conducted. Effects demonstrated anatomical selectivity, favoring hand musculature over proximal elbow musculature. Full article
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19 pages, 527 KB  
Article
Concentric Versus Eccentric Exercise-Induced Fatigue on Proprioception, Motor Control and Performance of the Upper Limb in Handball Players: A Retrospective Study
by Stelios Hadjisavvas, Michalis A. Efstathiou, Irene-Chrysovalanto Themistocleous and Manos Stefanakis
Life 2026, 16(3), 429; https://doi.org/10.3390/life16030429 - 6 Mar 2026
Viewed by 188
Abstract
Background: Upper-limb performance in handball depends on accurate shoulder sensorimotor control under high loads and fatigue. This study examined between-cohort differences associated with concentric versus eccentric exercise-induced fatigue in shoulder proprioception, kinesthesia, functional stability, and isometric force output in professional male handball players. [...] Read more.
Background: Upper-limb performance in handball depends on accurate shoulder sensorimotor control under high loads and fatigue. This study examined between-cohort differences associated with concentric versus eccentric exercise-induced fatigue in shoulder proprioception, kinesthesia, functional stability, and isometric force output in professional male handball players. Methods: This was a retrospective, quasi-experimental (non-randomized) between-cohort comparison of two previously collected cohorts who completed either a concentric (n = 46) or eccentric (n = 33) fatigue protocol, with pre- and post-fatigue assessments of joint repositioning sense (absolute angular error, AAE), threshold to detection of passive movement (TTDPM), Y Balance Test Upper Quarter (YBT-UQ), and the Athletic Shoulder (ASH) test. Results: Fatigue significantly increased AAE across all tested angles (Time: all p < 0.001), with a contraction-specific effect at end-range internal rotation (IR45°), where AAE increased more after concentric than eccentric fatigue (Time × Fatigue Type: p = 0.017; Δ = +1.34° (+61.8%) vs. +0.20° (+7.4%)). TTDPM increased after fatigue (p = 0.001) with no interaction (p = 0.968). YBT-UQ performance decreased after fatigue for all dominant-limb outcomes and for non-dominant inferolateral, superolateral, and composite scores (all p ≤ 0.018), but not for non-dominant anteromedial reach (p = 0.986); no Time × Fatigue Type interactions were detected for YBT-UQ outcomes (all p > 0.05). ASH force output decreased across all positions and both limbs (all p ≤ 0.002), with the dominant-limb Y position showing a greater decline following eccentric fatigue (Time × Fatigue Type: p = 0.030; e.g., ASH Y dominant Δ = −0.49 (−4.6%) vs. −1.43 N·kg−1 (−13.3%)). Conclusions: Exercise-induced fatigue impairs shoulder sensorimotor function and upper-limb performance in handball. Contraction-mode differences were small and task-specific in this between-cohort comparison, emerging primarily at end-range proprioception and selected isometric strength positions. These findings may inform the design of training programs that emphasize fatigue-resistant sensorimotor control and end-range strength, while causal inferences regarding contraction mode are not warranted given the non-randomized design. Full article
(This article belongs to the Special Issue Sports Biomechanics, Injury, and Physiotherapy)
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13 pages, 1469 KB  
Article
Beetroot Juice Enhances Nitrate Metabolism and Endothelial Function but Not Cardiovascular or Strength Performance in Bodybuilders with a History of Anabolic–Androgenic Steroid Abuse: A Crossover Trial
by Leonardo Santos L. da Silva, Leonardo Da Silva Gonçalves, Marcio F. Tasinafo Junior, Yaritza B. Alves Sousa, Macario Arosti Rebelo, Carolina S. Guimaraes, Jose E. Tanus-Santos, Carlos R. Bueno Junior and Jonas Benjamim
Antioxidants 2026, 15(3), 321; https://doi.org/10.3390/antiox15030321 - 4 Mar 2026
Viewed by 470
Abstract
Inorganic nitrate (NO3) has demonstrated therapeutic efficacy in several populations characterised by cardiovascular risk. However, it is unknown whether increasing nitric oxide (NO) bioavailability affects vascular and cardiovascular responses in men with androgenic–anabolic steroid (AAS) abuse. Objective: To investigate the [...] Read more.
Inorganic nitrate (NO3) has demonstrated therapeutic efficacy in several populations characterised by cardiovascular risk. However, it is unknown whether increasing nitric oxide (NO) bioavailability affects vascular and cardiovascular responses in men with androgenic–anabolic steroid (AAS) abuse. Objective: To investigate the effects of dietary NO3 on cardiovascular, autonomic, and strength performance in men with AAS abuse. Methods: In this double-blind, randomised, placebo-controlled crossover trial, participants consumed beetroot juice (12.8 mmol [800 mg] NO3) or a placebo (0.3 mmol NO3). After two hours, assessments included saliva collection, endothelial function, heart rate, and systolic (SBP) and diastolic (DBP) blood pressure at rest, during, and after an isometric handgrip test. Results: Thirteen resistance-trained males [mean (standard deviation) age: 31 (9) y; body mass index (BMI): 30 (4) kg/m2; SBP: 132 (3) mmHg; DBP: 70 (2) mmHg] completed the protocol. NO3-rich juice significantly increased salivary NO3 (40.6 μM, p < 0.001) and nitrite (NO2) (3.1 μM, p = 0.002) versus placebo. Flow-mediated dilation was greater with NO3 both at pre-exercise (2.37%, p = 0.02) and post-exercise (2.57%, p = 0.01). No between-group differences were observed in isometric strength (0.02 kgf, p = 0.99) or systolic/diastolic blood pressure across conditions. Conclusions: Dietary NO3 enhanced salivary NO2 and NO3 concentrations and modestly improved endothelial function but did not reduce the elevated blood pressure or alter cardiac autonomic responses associated with AAS abuse. Full article
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20 pages, 1905 KB  
Article
Directional Asymmetry of Crossover Neuromuscular Fatigue Following Unilateral Handgrip Exercise in Adults and Prepubertal Children
by Aymen Ben Othman, Wissem Dhahbi, Manel Bessifi, Halil İbrahim Ceylan, Valentina Stefanica, Rihab Moncer and Helmi Ben Saad
Medicina 2026, 62(3), 471; https://doi.org/10.3390/medicina62030471 - 2 Mar 2026
Viewed by 178
Abstract
Background and Objectives: This study investigated whether crossover neuromuscular fatigue following unilateral handgrip exercise exhibits directional asymmetry, testing whether dominant-limb fatigue produces greater contralateral performance decrements than non-dominant-limb fatigue in adults and pre-peak-height-velocity children. Materials and Methods: Thirty-three healthy, right-handed males [...] Read more.
Background and Objectives: This study investigated whether crossover neuromuscular fatigue following unilateral handgrip exercise exhibits directional asymmetry, testing whether dominant-limb fatigue produces greater contralateral performance decrements than non-dominant-limb fatigue in adults and pre-peak-height-velocity children. Materials and Methods: Thirty-three healthy, right-handed males (16 adults: 22.5 ± 1.6 years; 17 pre-peak-height-velocity boys: 11.2 ± 0.8 years, maturity offset −2.2 ± 0.4 years) completed three counterbalanced experimental sessions (48–72 h apart): dominant-arm fatigue, non-dominant-arm fatigue, and control. The fatigue protocol consisted of 20 consecutive 6 s maximal voluntary isometric handgrip contractions. Primary outcomes were percentage changes in maximal voluntary isometric contraction of the contralateral limb across handgrip, elbow flexor, and elbow extensor muscle groups. Results: The experimental condition explained approximately 64% of crossover variance in adults (ηp2 = 0.650, ηG2 = 0.421) and children (ηp2 = 0.638, ηG2 = 0.448; both p < 0.001). Dominant-limb fatigue elicited substantially greater contralateral decrements than non-dominant-limb fatigue in adults (−11.00% vs. −3.92%, dz = −1.07) and children (−12.71% vs. −3.08%, dz = −1.33), representing 2.5- to 3.5-fold greater transfer efficiency (both p < 0.001). Age-group comparisons revealed no differences in crossover susceptibility (p = 0.627, ηp2 = 0.008), with equivalence testing confirming developmental invariance. Crossover effects extended to heterologous proximal muscles without magnitude differences (p > 0.13). Conclusions: Crossover fatigue (contralateral performance decrement following unilateral exercise) exhibited directional asymmetry, with dominant-limb protocols eliciting 2.5- to 3.5-fold greater contralateral decrements. This pattern aligns with asymmetric transcallosal inhibitory projections demonstrated in prior transcranial magnetic stimulation studies, though direct neurophysiological confirmation was not obtained. Functional equivalence between pre-peak-height-velocity children and adults indicates that interhemispheric transfer mechanisms achieve operational maturity before peak height velocity. Extension to heterologous muscles implicates supraspinal mechanisms. The findings establish normative parameters for clinical populations with compromised transcallosal integrity. Full article
(This article belongs to the Section Sports Medicine and Sports Traumatology)
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14 pages, 615 KB  
Article
Effects of Caffeine on Voluntary Force Estimation During Isometric Exercises
by Ester Jiménez-Ormeño, Verónica Giráldez-Costas, Beatriz Lara-López, María Menchén-Rubio and Carlos Ruiz-Moreno
Sports 2026, 14(3), 90; https://doi.org/10.3390/sports14030090 - 2 Mar 2026
Viewed by 258
Abstract
Background: Caffeine is widely used as an ergogenic aid to enhance strength performance; however, its effects on perceptual accuracy during submaximal force regulation remain unclear, particularly in multi-joint isometric tasks. This study examined whether caffeine ingestion influences maximal isometric force production and the [...] Read more.
Background: Caffeine is widely used as an ergogenic aid to enhance strength performance; however, its effects on perceptual accuracy during submaximal force regulation remain unclear, particularly in multi-joint isometric tasks. This study examined whether caffeine ingestion influences maximal isometric force production and the accuracy of voluntary submaximal force estimation during complex isometric exercises. Methods: Seventeen recreationally trained participants completed a randomized, double-blind, placebo-controlled crossover study. Participants ingested either caffeine (4 mg·kg−1 body mass) or a placebo before performing an isometric squat test (ISqT) and an isometric mid-thigh pull test (IMTP). Maximal voluntary contractions were assessed, followed by freely estimated submaximal efforts at 50% and 75% of perceived maximal force. Relative peak force and discrepancies between prescribed and exerted force (estimation error) were analyzed, with discrepancies calculated as the difference between exerted force and the prescribed target intensity. Results: Caffeine ingestion did not significantly affect relative peak force during maximal isometric efforts nor improve the accuracy of voluntary submaximal force estimation. Regardless of supplementation conditions, participants consistently misestimated submaximal efforts, tending to overproduce force, particularly at lower intensities. The IMTP showed a closer approximation to prescribed submaximal targets than the ISqT. Conclusions: Ingesting 4 mg·kg−1 of caffeine does not enhance maximal isometric force output or perceptual accuracy during voluntary submaximal force regulation in multi-joint isometric tasks. Prescribing isometric intensity based solely on perceived effort may therefore be unreliable under these specific testing conditions, particularly at lower intensities. Full article
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20 pages, 5414 KB  
Article
Agreement-Based Validation of ISOMETRO for Upper-Limb Isometric Tension Measurements
by José Luis González-Montesinos, Jorge del Rosario Fernández-Santos, David Jiménez-Pavón, Alejandro Sánchez-Delgado, Rubén Aragón-Martín, Juan Manuel Escudier-Vázquez and Vanesa España-Romero
Sensors 2026, 26(5), 1504; https://doi.org/10.3390/s26051504 - 27 Feb 2026
Viewed by 314
Abstract
Muscular fitness is a key component of health and athletic performance, and isometric strength is a widely used indicator. This study reports an agreement-based validation of the Isometric Strength Measurement Device (ISOMETRO) for upper-limb isometric tension measurements under controlled laboratory conditions. Twenty-one healthy [...] Read more.
Muscular fitness is a key component of health and athletic performance, and isometric strength is a widely used indicator. This study reports an agreement-based validation of the Isometric Strength Measurement Device (ISOMETRO) for upper-limb isometric tension measurements under controlled laboratory conditions. Twenty-one healthy young amateur rock climbers (11 men and 10 women) performed four upper-limb tensile tests (shoulder adduction at 90°, shoulder adduction at 60°, shoulder extension at 90°, and elbow extension at 90°). Agreement with an independent criterion device was evaluated using a force plate, while a series-connected load cell was used as an internal consistency check of the measurement chain. Linear mixed-effects models showed that ISOMETRO strongly predicted force plate values (β = 0.999, SE = 0.002, p < 0.001), with a marginal R2 > 0.99. Bland–Altman analysis indicated negligible bias (−0.08 N) and narrow limits of agreement (−4.97 to 4.81 N), and concordance was excellent (CCC ≥ 0.996). The series-connected load cell comparison also showed near-unity agreement (β = 0.998, SE = 0.003, p < 0.001), supporting internal measurement chain integrity. These findings support excellent agreement between ISOMETRO and force plate measurements for upper-limb tensile isometric testing along the vertical axis in young amateur rock climbers under controlled laboratory conditions. However, given the specific sample characteristics and the strictly vertical laboratory configuration, these results should not be generalized to other populations, joint angles, force directions, or non-laboratory environments without further validation. Further studies are needed to confirm performance in more diverse contexts and to establish reliability for repeated-measurement applications. Full article
(This article belongs to the Special Issue Smart Sensors and Sensing Technologies for Biomedical Engineering)
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20 pages, 543 KB  
Article
Effects of Adding Posterior Ankle Joint Mobilization to Eccentric Training on Ankle Range of Motion and Athletic Performance in Basketball Athletes with Restricted Ankle Dorsiflexion: A Randomized Controlled Trial
by Vasileios Georgoulas, Ilias Kallistratos, Thomas Apostolou, Konstantinos Kasimis, Dimitrios Lytras and Paris Iakovidis
J. Funct. Morphol. Kinesiol. 2026, 11(1), 92; https://doi.org/10.3390/jfmk11010092 - 25 Feb 2026
Viewed by 261
Abstract
Background: Restricted ankle dorsiflexion is common in basketball athletes and has been associated with altered lower-limb mechanics and reduced athletic performance. Although ankle joint mobilization is widely used to improve mobility, its effects on athletic performance remain unclear. The aim of this study [...] Read more.
Background: Restricted ankle dorsiflexion is common in basketball athletes and has been associated with altered lower-limb mechanics and reduced athletic performance. Although ankle joint mobilization is widely used to improve mobility, its effects on athletic performance remain unclear. The aim of this study was to examine whether adding posterior ankle joint mobilization to a structured exercise-based program incorporating eccentric strengthening and stretching improves ankle mobility and athletic performance in basketball athletes with restricted dorsiflexion. Primary outcomes were dorsiflexion range of motion (DF-ROM) and the Weight-Bearing Lunge Test (WBLT); secondary outcomes included jump performance, hop tests, Reactive Strength Index, Fatigue Index, and maximal isometric strength. Methods: In this randomized controlled trial, 38 basketball athletes (mean age 21.26 ± 2.52 years) with unilateral restricted ankle dorsiflexion were randomly allocated to an exercise-only group (n = 19) or to an exercise plus talocrural mobilization group (n = 19). The intervention lasted 5 weeks, with assessments performed at baseline, post-intervention, and at a 3-month follow-up. Results: Both groups improved ankle dorsiflexion; however, greater gains were observed in the intervention group for both dorsiflexion range of motion (DF-ROM; interaction p < 0.001; mean difference [MD] = 3.52° post-intervention and MD = 5.17° at follow-up) and the Weight-Bearing Lunge Test (WBLT; interaction p < 0.001; MD = 1.39 cm and MD = 1.34 cm, respectively). The intervention group showed superior improvements in countermovement jump and Triple Hop Test performance (both p < 0.001), as well as a small but statistically significant advantage in the Single Hop Test (p = 0.015). No between-group differences were found for the 6 m timed hop test, Reactive Strength Index, Fatigue Index, or maximal isometric strength (p > 0.05). Conclusions: Adding ankle joint mobilization to an eccentric strengthening and stretching program produced greater improvements in dorsiflexion and jump performance than exercise alone, without affecting speed, reactive ability, or maximal strength. Ankle mobilization may be a useful adjunct for improving functional mobility and selected performance outcomes in basketball athletes. Full article
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17 pages, 2039 KB  
Article
Short-Term Effects of Broccoli-Derived Glucoraphanin on Recovery from Eccentric Muscle Damage: A Double-Blind Randomized Crossover Study
by Leonardo Cesanelli, Rono Thomas, Mantas Mickevičius, Audrius Sniečkus, Dalia Mickevičienė, Tomas Venckūnas, Arvydas Stasiulis and Sigitas Kamandulis
Nutrients 2026, 18(4), 710; https://doi.org/10.3390/nu18040710 - 23 Feb 2026
Viewed by 604
Abstract
Background/Objectives: Broccoli-derived glucoraphanin (a sulforaphane precursor that activates Nrf2 defenses) may aid repair; however, its short-term effects in humans remain unknown. This study aimed to evaluate whether short-term supplementation with broccoli-derived glucoraphanin improves recovery from exercise-induced muscle damage. We hypothesized that short-term [...] Read more.
Background/Objectives: Broccoli-derived glucoraphanin (a sulforaphane precursor that activates Nrf2 defenses) may aid repair; however, its short-term effects in humans remain unknown. This study aimed to evaluate whether short-term supplementation with broccoli-derived glucoraphanin improves recovery from exercise-induced muscle damage. We hypothesized that short-term supplementation with broccoli-derived glucoraphanin would attenuate exercise-induced muscle damage and accelerate recovery. Methods: In a randomized, double-blind, placebo-controlled crossover design, fifteen participants consumed either high-glucoraphanin broccoli powder (320 μg) or placebo for two weeks, followed by elbow flexor eccentric exercise. Strength, soreness, creatine kinase (CK), range of motion (ROM), arm girths, and ultrasound-assessed muscle and tendon morphology were measured at baseline, immediately post-exercise, and at 48 and 96 h post-exercise. Results: Significant main effects of time were observed for isometric and isokinetic torque (p < 0.05), CK (p < 0.05), soreness (p < 0.05), and structural swelling markers (p < 0.05), confirming exercise-induced muscle damage. However, there were no significant Time × Supplement interactions for any variable (p > 0.05), indicating that glucoraphanin did not influence recovery dynamics. Conclusions: These findings suggest that short-term high-dose broccoli supplementation reconstituted with hot water does not modulate recovery following eccentric muscle damage under the conditions tested, including the chosen preparation method and experimental context. Full article
(This article belongs to the Special Issue Nutrition Strategy and Resistance Training)
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18 pages, 1820 KB  
Article
Development of an RPE-Based Prediction Model for Trunk Muscle Activation During Water Inertia Load Exercise: A Pilot EMG Study
by Shuho Kang and Ilbong Park
J. Funct. Morphol. Kinesiol. 2026, 11(1), 89; https://doi.org/10.3390/jfmk11010089 - 21 Feb 2026
Viewed by 327
Abstract
Background: Water inertia load training using equipment such as water vests provides unstable resistance that enhances trunk muscle activation. However, practical methods for prescribing exercise intensity without expensive electromyography (EMG) equipment remain limited. This pilot study aimed to develop prediction models for estimating [...] Read more.
Background: Water inertia load training using equipment such as water vests provides unstable resistance that enhances trunk muscle activation. However, practical methods for prescribing exercise intensity without expensive electromyography (EMG) equipment remain limited. This pilot study aimed to develop prediction models for estimating trunk muscle activation using rating of perceived exertion (RPE) during water inertia load exercises. Methods: Seventeen healthy adults (20.45 ± 2.02 years) performed lateral trunk flexion exercises wearing a water vest at five progressive loads (8–16 kg in 2 kg increments). Surface EMG was recorded from four trunk muscles (rectus abdominis, external oblique, internal oblique, erector spinae) and normalized to maximal voluntary isometric contraction (%MVIC). Rating of perceived exertion (RPE) was assessed using the Borg CR-10 scale. Load-dependent changes in muscle activation were examined using repeated-measures ANOVA, and relationships between RPE and EMG were analyzed using regression and linear mixed-effects models. Results: All trunk muscles showed significant increases in activation with increasing load (all p < 0.001, ηp2 = 0.381). RPE demonstrated significant positive correlations with all abdominal muscles (r = 0.37–0.46, p < 0.001). Simple regression analyses indicated predictive accuracy (R2 = 0.267), representing a 29% increase compared with the strongest individual muscle model. Linear mixed-effects modeling confirmed RPE as a significant predictor after accounting for inter-individual variability. Conclusions: This pilot study provides preliminary evidence that RPE can be used to estimate trunk muscle activation during water inertia load exercise. The proposed composite activation index enhances prescription when EMG measurement is not feasible. Full article
(This article belongs to the Section Functional Anatomy and Musculoskeletal System)
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17 pages, 1185 KB  
Article
Sex Differences in the Acute Effects of Early Partial and Total Sleep Deprivation on Strength, Power, and Endurance Performance in Resistance-Trained Participants
by Marta del Val-Manzano, Juan Jesús Montalvo-Alonso, Paola Gonzalo-Encabo, David Valadés, Carmen Ferragut and Alberto Pérez-López
J. Funct. Morphol. Kinesiol. 2026, 11(1), 83; https://doi.org/10.3390/jfmk11010083 - 19 Feb 2026
Viewed by 311
Abstract
Background: Sleep is essential for athletic performance, yet the specific effects of sleep deprivation are not well defined. Evidence in resistance-trained populations is limited regarding sex-specific responses and velocity-based performance across different loads. Purpose: This study examined sex differences in the impact [...] Read more.
Background: Sleep is essential for athletic performance, yet the specific effects of sleep deprivation are not well defined. Evidence in resistance-trained populations is limited regarding sex-specific responses and velocity-based performance across different loads. Purpose: This study examined sex differences in the impact of total (0 h) and partial (4 h) sleep deprivation versus normal sleep (8 h) on strength, power, and endurance performance in resistance-trained individuals. Methods: Twenty-four resistance-trained participants (male/female, 12/12; age: 22 ± 3 years) completed a randomized, cross-over, counterbalanced trial including one baseline control night (8 h at home sleep) and three experimental conditions in the laboratory: (a) 8 h sleep (NS), (b) 4 h sleep (ESD), (c) 0 h sleep (SD). Strength was assessed at 25%, 50%, 75%, 90% and 100% 1RM for bench press and back squat (half-squat depth, ~90° knee flexion), in a Smith machine, followed by a muscular endurance test at 65% 1RM (set-to-failure). Isometric strength and vertical jump test were also performed. Results: At 50% 1RM, significant sleep and sleep-by-sex effects were observed for Vmean in both exercise (p < 0.05, ηp2 > 0.09), an effect only noted in males, with reduced performance under ESD and SD compared to NS (7–13%, p < 0.05, g > 0.50). In the muscular endurance test, sleep and sleep-by-sex effects were found (p < 0.05, ηp2 < 0.22), an effect only found in females during the back squat, showing performance declines in Vmean in ESD and SD compared to NS (7–12%, p < 0.05, g > 0.2). Conclusions: Total and partial sleep deprivation impairs muscular performance differently by sex. Males experienced reduced strength at moderate loads, while females showed declines in muscular endurance. Full article
(This article belongs to the Special Issue New Insights into Muscle Fatigue and Recovery)
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15 pages, 1760 KB  
Article
Comparative Analysis of Quadriceps Electromyography During Bodyweight Strength Exercises
by Jesús Vera-Cartagena, Francisco J. Vera-Garcia, Aarón Miralles-Iborra, Juan Del Coso and Víctor Moreno-Pérez
Appl. Sci. 2026, 16(4), 1940; https://doi.org/10.3390/app16041940 - 15 Feb 2026
Viewed by 1430
Abstract
Background: Although numerous exercises are prescribed for quadriceps femoris (QF) injury prevention and rehabilitation, few studies have compared QF muscle activation across commonly used bodyweight strength tasks. This study compared EMG activity of the rectus femoris proximal (RFP), rectus femoris medial (RFM), vastus [...] Read more.
Background: Although numerous exercises are prescribed for quadriceps femoris (QF) injury prevention and rehabilitation, few studies have compared QF muscle activation across commonly used bodyweight strength tasks. This study compared EMG activity of the rectus femoris proximal (RFP), rectus femoris medial (RFM), vastus lateralis (VL), and vastus medialis (VM) during seven bodyweight exercises with different stance positions. Methods: Twenty healthy male amateur football players performed three staggered-stance exercises (Split Squat, Bulgarian Split Squat, Backward Lunge), three parallel-stance exercises (Half-Squat, Russian Belt, Reverse Nordic), and one single-leg stance exercise (Lateral Step-Down). Surface EMG signals were recorded, and mean peak EMG values for each exercise were averaged and normalized to maximal isometric voluntary contraction (MVIC). Results: The highest VM and VL activation occurred during the Bulgarian Split Squat (VM: 85.4%; VL: 67.6% MVIC) and Backward Lunge (VM: 74.5%; VL: 59.9% MVIC). RFP and RFM showed the greatest activation during the Russian Belt (RFP: 49.8%; RFM: 39.6% MVIC) and Backward Lunge (RFP: 40.4%; RFM: 31.4% MVIC). VM and VL activation were significantly higher than RFP and RFM activation for all exercises except for Russian Belt and Reverse Nordic (p < 0.005). Conclusions: Exercises imposing greater knee stability demands preferentially activated VM and VL, whereas exercises with longer knee extensor lever arms maximized rectus femoris activation. Full article
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10 pages, 875 KB  
Article
Effects of a Motion-Triggered Neuromuscular Electrical Stimulation Strength Program on Shoulder Strength and Throwing Velocity in Elite Handball Players
by Sebastian Conner-Rilk, Fabian M. Tomanek, Brenda Laky, Philipp R. Heuberer, Jakob E. Schanda and Ulrich Lanz
J. Clin. Med. 2026, 15(4), 1420; https://doi.org/10.3390/jcm15041420 - 11 Feb 2026
Viewed by 301
Abstract
Background: To evaluate the effects of a motion-triggered neuromuscular electrical stimulation (NMES) shoulder strengthening program on rotational shoulder strength and throwing velocity in healthy, elite-level handball players. Methods: Fourteen male handball players were randomly allocated (1:1) to either the NMES or control group. [...] Read more.
Background: To evaluate the effects of a motion-triggered neuromuscular electrical stimulation (NMES) shoulder strengthening program on rotational shoulder strength and throwing velocity in healthy, elite-level handball players. Methods: Fourteen male handball players were randomly allocated (1:1) to either the NMES or control group. Participants were assessed by a blinded investigator at baseline and after 6 weeks for clinical status, isometric dynamometer-based external (ER) and internal rotational (IR) maximal shoulder strength, and handball endurance and maximal throwing velocity (7 m free throw). Between time points, NMES subjects completed a standardized motion-triggered NMES shoulder strengthening program (3 sessions/week, 30 min for 6 weeks), whereas controls performed a conventional standardized strength program. Results: After completion of the motion-triggered NMES program, all NMES participants (100%) demonstrated significant gains in isometric ER strength (+1.4 ± 1.1 kg, p = 0.016) compared with 43% of controls, who demonstrated no overall improvement (−0.2 ± 1.8 kg, p = 0.740). Similarly, a significantly greater proportion of NMES participants improved endurance throwing velocity compared with controls (100% vs. 29%, p = 0.004), with a mean increase of +2.9 ± 2.8 km·h−1 (p = 0.0.56). Maximum throwing velocity showed no between-group differences in the proportion of athletes with improved results (p = 0.899). Conclusions: A six-week motion-triggered NMES shoulder strengthening program improved external rotation strength and increased the proportion of athletes demonstrating enhanced endurance throwing velocity under fatigued conditions. However, when compared with conventional exercise alone, NMES did not confer additional benefits for maximal throwing velocity in this study. Therefore, NMES should be regarded as a complementary modality rather than a substitute for established shoulder strengthening exercises. Full article
(This article belongs to the Special Issue Sports Injury: Clinical Prevention and Treatment)
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14 pages, 340 KB  
Article
Acute Effects of Nutritional and Physical Recovery Strategies on Exercise Performance, Muscle Damage, and Fatigue in Elite Basketball Players: A Pilot Randomized Crossover Trial
by Alberto Marín-Galindo, Alejandro Perez-Bey, Juan M. Escudier-Vázquez, Daniel Velázquez-Díaz, Julio Calleja-González, Carmen Vaz-Pardal, Juan Corral-Pérez and Jesus G. Ponce-Gonzalez
Life 2026, 16(2), 275; https://doi.org/10.3390/life16020275 - 5 Feb 2026
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Abstract
Background: Due to the congested competition calendar and the high physical demands of elite basketball, the selection of effective recovery strategies is essential to optimize performance and reduce exercise-induced fatigue and muscle damage. This pilot study aimed to examine the acute effects of [...] Read more.
Background: Due to the congested competition calendar and the high physical demands of elite basketball, the selection of effective recovery strategies is essential to optimize performance and reduce exercise-induced fatigue and muscle damage. This pilot study aimed to examine the acute effects of different nutritional and physical recovery strategies on exercise performance, muscle damage, and perceived fatigue and exertion in elite basketball players. Methods: Fifteen elite male basketball players participated in this pilot randomized crossover trial and completed four recovery conditions: cold-water immersion (CWI), active recovery (ACT), protein–carbohydrate supplementation (SUP), and placebo (PLA). Following a basketball-specific fatigue protocol, creatine kinase, countermovement jump performance, isometric strength, 10 m sprint, and 4 × 10 m shuttle run tests were assessed at baseline, immediately post-exercise, and 24 h post-exercise. Perceived fatigue and rate of perceived exertion were measured at baseline, immediately post-exercise, immediately after the recovery intervention, and 24 h post-exercise. Results: The three recovery methods attenuated the 24 h exercise-induced increase in CK compared with the placebo condition (p > 0.05). CWI, SUP and ACT decreased fatigue and RPE immediately after their application (p < 0.05), while PLA kept them elevated. CWI was associated with a significant improvement in 4 × 10 m SRT performance (p = 0.027). Conclusions: Nutritional supplementation and physical recovery strategies effectively attenuated exercise-induced muscle damage and fatigue in elite basketball players. However, CWI demonstrated the most pronounced acute benefits for physical performance recovery. Full article
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12 pages, 233 KB  
Article
Can Exercise Training Improve the Quality of Life and Physical Function in Multiple Myeloma Patients?: Discussing the Progression of the Training Stimulus
by Polyxeni Spiliopoulou, Evangelos Eleutherakis-Papaiakovou, Magdalini Migkou, Nikolaos Kanellias, Ioannis Ntanasis-Stathopoulos, Panagiotis Malandrakis, Foteini Theodorakakou, Despina Fotiou, Pantelis Rousakis, Chrysanthi Panteli, Evangelos Terpos, Maria Gavriatopoulou, Ourania E. Tsitsilonis, Efstathios Kastritis, Meletios Athanasios Dimopoulos and Gerasimos Terzis
Sports 2026, 14(2), 61; https://doi.org/10.3390/sports14020061 - 4 Feb 2026
Viewed by 385
Abstract
Background: Previous studies have reported no improvements in quality of life or physical function following exercise training in patients with multiple myeloma, without a clear explanation. The purpose of the present study was to examine the effects of an exercise-training intervention on these [...] Read more.
Background: Previous studies have reported no improvements in quality of life or physical function following exercise training in patients with multiple myeloma, without a clear explanation. The purpose of the present study was to examine the effects of an exercise-training intervention on these outcomes and to determine whether the observed results could be explained by the characteristics of the training program. Methods: Sixteen patients with multiple myeloma who had completed first-line induction therapy were assigned to two groups. One group (2 men, 6 women, 52.6 ± 10.3 years) commenced maintenance therapy only, while the other group (2 men, 6 women, 58.8 ± 7.1 years) initiated maintenance therapy combined with a supervised exercise training program conducted twice per week. Each exercise session included 30 min of cycling and seven resistance exercises targeting the major muscle groups. The intervention lasted 4.4 ± 1 months. QoL, the six-minute walking test, handgrip strength, maximal aerobic power, maximum isometric contraction across 14 positions, and bone density were assessed before and after the intervention. Results: The six-minute walking test distance significantly increased in the exercise group (9.36 ± 6.88%, p = 0.001), while no change was observed in the control group (3.34 ± 5.68%, p = 0.162); however, the difference between groups was not statistically significant (p = 0.076). QoL and maximal aerobic power remained unchanged in both groups, while maximal isometric strength increased significantly in both groups. Conclusions: The progression of the training stimulus appears to be inconsistent in this specific population, potentially limiting improvements in quality of life and physical function outcomes. Supervision appears to be necessary for exercise training in patients with multiple myeloma. Future research should investigate alternative exercise modalities in these patients. Full article
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