Physiologia

Background: Combining pool-based and resistance workouts, both in the pool and on dry land, is a valuable approach to enhancing swimming performance. However, few investigations have been conducted on this topic. Through a randomized controlled trial study, we investigated the effects of a 10-week concurrent resistance training program, which integrated resistance workouts both in the pool and on dry land on tethered force, lower limbs strength, anaerobic critical velocity, and swimming performance, in regional age-group breaststroke swimmers. Methods: Regional age-group swimmers (N = 24, males) were randomly divided into two groups. The experimental group (EG: 15.1 ± 0.5 years old) performed combined pool-based + resistance workouts, both in the pool and on dry land. The control group (CG: 15.1 ± 0.7 years old) performed their usual training regime, i.e., pool-based + resistance workouts on dry land only. The tethered swimming force, muscular strength, anaerobic critical velocity, and swimming performance and technique of the swimmers were evaluated before the training program began and after 10 weeks. Results: Improvements were observed in the EG vs. the CG in terms of the mean force (30.04%, p = 0.02; d = 0.75), one-repetition maximum back squat (20.57%, p = 0.01; d = 2.05), maximal force (19.23%, p = 0.03; d = 0.69), and anaerobic critical velocity (4.2%, p = 0.04; d = 0.61). The 50 and 200 m breaststroke performance times improved (4.3 and 5.4%, p = 0.01, d = 0.88–0.92, respectively) after 10 weeks. Conclusions: With the increasing demands of contemporary swimming competitions, which often include heats, semifinals, and finals, achieving optimal physical fitness to compete at an elite level, in every round, is vital for swimmers. The combination of resistance training workouts both in the pool and on dry land seems to enhance swimming performance in age-group swimmers, particularly in sprint to middle-distance breaststroke swimmers. Full article

Background: Tendon lesions affecting the proximal rectus femoris (PRF) muscle represent about 1.5% of hip injuries. Most acute cases are managed conservatively with physiotherapy. There is a lack of consensus regarding surgical intervention for chronic injuries. This article, alongside a literature review, presents a case of anatomical surgical reinsertion for chronic complete avulsion rupture of the PRF tendon. Case Report: A 34-year-old amateur athlete experienced acute inguinal pain from overexertion, with conservative treatment having failed over 3 months. Seven months later, proximal tendon rupture involving both PRF muscle heads was confirmed. An anterior Hueter approach released the tendon from the adhesions and fibrosis. The direct portion was reinserted into the inferior anterior iliac spine, and the reflex portion was reattached to the supraacetabular groove. The patient showed excellent improvement on the modified Harris Hip and Lysholm–Tegner scales. The quadriceps muscle force decreased by 20% compared to the contralateral leg at 3 months, reducing to 4% by 12 months. Normal activities resumed after six weeks, and sports resumed after 4 months. Conclusions: The patient experienced significant postoperative improvement, as shown by the enhanced functional scores and muscle force recovery over one year. The success of the anatomical reconstruction in restoring tendon continuity underscores the importance of tendon healing mechanisms, including tissue remodeling and revascularization, in chronic avulsion injuries. This case highlights the efficacy of anatomical reconstruction for chronic PRF tendon avulsion. The literature review offers further insights into treatment options and the physiological basis of recovery for such injuries. Full article

Background: Ketone body supplementation has emerged as a potential ergogenic aid in cycling. Exogenous ketones, primarily in the form of beta-hydroxybutyrate, offer an alternative fuel source, bypassing the need for strict ketogenic diets. However, the science surrounding their efficacy remains complex, with mixed field findings and unexplored mechanisms. Methods: A narrative review of the current literature was conducted, synthesizing studies on the metabolic and cognitive effects of ketone bodies in cycling. The review included an examination of human and mechanistic studies, along with emerging hypotheses on ketone bodies and their role in modulating red blood cell production and recovery processes. Results: Ketone body supplementation can theoretically spare glycogen, reduce muscle protein breakdown, enhance fat oxidation, and improve recovery by mitigating oxidative stress and inflammation. Additionally, ketone bodies may support cognitive function, reducing perceived mental fatigue. Preliminary evidence also suggests a potential role in modulating erythropoietin levels through histone acetylation, though further research is needed to establish its impact on oxygen delivery. Despite the theoretical potential, the practical assessment of field studies shows disappointing effects on performance from ketone body supplementation. Conclusions: While ketone bodies offer several potential benefits for cyclists, the variability in individual responses, lack of long-term data, and inconsistent findings in performance studies highlight the need for further research. Optimizing dosage, timing, and understanding the broader implications of ketone body supplementation will be crucial for their practical application in cycling. Full article

Military personnel routinely complete stressful training exercises in harsh environmental conditions to prepare for intense operational demands. Purpose: This study determined the effect of environmental conditions on salivary hormone profiles in Marines during a mountain warfare training exercise (MTX). Methods: Two cohorts of Marines (age 22 ± 4, height 174 ± 7 cm, body mass 79.2 ± 11.5 kg) completed an MTX (elevation 2100 to 3500 m) in the Fall (n = 63, temperature 11 ± 2 °C) and Winter (n = 64, temperature −5 ± 4 °C). Saliva samples were provided before (PRE), during (MID), and after (POST) the MTX, and were assayed for α-amylase, cortisol, DHEA, testosterone, and osteocalcin. Results: Linear mixed models were used to determine significant interactions (time × season) and found differences in DHEA, testosterone, and osteocalcin. Testosterone and DHEA were lower at MID compared to PRE and POST during the Fall MTX. Testosterone was higher at MID compared to PRE and POST during the Winter MTX, while DHEA remained stable. Osteocalcin was higher in Fall participants compared to Winter but demonstrated a similar trend to increase at MID and decrease at POST in both groups. Cortisol was higher during the Winter MTX compared to the Fall. Conclusions: These findings highlight the differential physiological stress responses in varying seasonal conditions, suggesting the need for tailored training strategies to enhance military readiness and prevent hormonal dysregulation. Further research is needed to elucidate the mechanisms underlying these seasonal effects. Full article

The brain-derived neurotrophic factor (BDNF) is a crucial protein in the development of the cognitive system. It regulates the growth of neurons and glial cells, synaptic plasticity, and neuroprotection. Background/Objectives: It has been suggested that high-intensity exercise could modulate the mechanisms of BDNF release, with potentially significant implications in the professional sports world. However, this is not yet fully proven, and the underlying physiological alterations are unknown. Methods: This paper reviews the current scientific literature to clarify the uncertainties about how high-intensity physical exercise influences BDNF release and its relationship with high-performance sports. Results: Strenuous exercise appears to increase BDNF synthesis through the action of lactate and the PGC-1α/FNDC5 pathway. Additionally, cognitive function has been described as an element to consider for maximizing sports performance. Conclusions: In this regard, this review provides a solid starting point for further investigation into the molecular mechanisms that promote BDNF expression mediated by exercise, as well as for seeking a direct correlation between the role of cognitive development and athletic performance in high-performance athletes. Full article

Background: Individuals observe Ramadan fasting for ~11 h per day for 28–30 days, which can negatively affect lean mass. Resistance training or increased protein intake can potentially preserve lean mass in these individuals. Methods: Twenty-three young and healthy adult Muslim men were divided into three groups: Ramadan fasting (RAM), Ramadan fasting combined with resistance training (RAM + RT), and Ramadan fasting combined with 30 g of daily whey protein (RAM + WH). Participants’ body mass, body mass index (BMI), body fat percentage, fat mass, and lean mass were measured the week prior to and during the last week of Ramadan via a stadiometer and dual-energy X-ray absorptiometry (DXA). Results: Body mass (kg) was decreased for all three groups (RAM = −1%, RAM + RT = −1%, RAM + WH = −1.3%; p = 0.033), though there were no differences between groups. Lean mass (kg) was decreased for all three groups (RAM = −1%, RAM + RT = −1%, RAM + WH = −2%; p = 0.013), though there were no differences between groups. No differences were observed for body weight, BMI, or body fat percentage. Conclusions: These results indicate resistance training or whey protein did not provide any advantage for preserving lean mass in individuals participating in Ramadan fasting. Full article

Background/Objectives: Endurance triathlons impose substantial physiological stress, yet the effects of short-course formats remain relatively unexplored. This preliminary study presents novel findings on proteinuria and hydration levels in well-trained triathletes. Methods: 27 participants (41.9 ± 7.4 years) who completed a sprint triathlon consisting of a 1500 m swim, 26 km cycle, and 8 km run. Urine samples were collected before and after the race. Results: Our results revealed a significant increase in post-race proteinuria cases from four to nine (p = 0.03) and the first reported case of post-race urobilinuria and ketoacidosis in this context. Additionally, pre-race glucosuria, present in nine cases, decreased to three post-race. Hematuria cases decreased from six to two (p = 0.13) and pre-race leukocyturia resolved post-race. There was a significant increase in urine specific gravity (from 1.018 to 1.023, p = 0.03), indicating dehydration. Conclusions: Short-course triathlons significantly induced post-race proteinuria, urobilinuria, and dehydration, highlighting the substantial physiological stress on kidney function and hydration status despite the shorter distances. These findings underscore the importance of monitoring urinary biomarkers and hydration levels in athletes before and after competition. Full article

Whilst cold therapies such as cold-water immersion are regularly used in practice, the practical application does not always align with best practices. In this commentary, we highlight the key components of the British Association of Sport and Exercise Sciences (BASES) Expert Statement on the use of cooling therapies for post-exercise recovery and provide additional discussion on the empirical evidence and rationale that informed our perspective. We developed a series of specific questions to ensure that cold therapy recovery protocols are context-specific and tailored to the needs of the individual athletes. These questions, which cover the WHEN, WHAT, and HOW of cold therapy, were central to the development of the Expert Statement. This was presented as a decision tree to ensure that key messages could be concisely disseminated across a range of sporting environments and populations (e.g., gyms, locker rooms, and treatment rooms), supporting and informing decision-making for those wanting to use cold therapy to assist their recovery in line with previously published peer-reviewed work. Discussion points included the suitability of cooling therapies in some contexts, how athletes’ choice of cooling mode should be largely driven by practicalities (e.g., budget and availability), and, lastly, future research directions. Full article

Background/Objectives: This study aimed to evaluate the effects of an 8-week combined plyometric and resistance training program on the physical fitness (PF) of adolescent girls aged 12 to 15 years. The objective was to determine whether combined training (CT) would yield greater improvements in performance measures compared to resistance training (RT) alone. Methods: Forty-seven adolescent girls were randomly assigned to either the CT group or the RT group. Performance measures such as the 20 m sprint, squat jump, vertical jump, handgrip strength, and flexibility (sit and reach test) were assessed before and after the 8-week intervention. Changes in these measures were analyzed to compare the effects of the two training approaches. Results: The CT group showed a significant reduction in sprint time (−6.5%) compared to the RT group (−4.1%), although the difference was not statistically significant. Squat jump height improved significantly by 5.6% in the CT group compared to 1.1% in the RT group (p < 0.05). Similarly, vertical jump height increased by 6.7% in the CT group and by 2.4% in the RT group (p < 0.05). Handgrip strength improved by 7.5% in the CT group and 4.6% in the RT group, with no significant differences between the groups. Flexibility showed slight, non-significant improvements in both groups. Conclusions: The findings suggest that a combined plyometric and RT program is more effective in enhancing explosive power, specifically squat and vertical jump performance, in adolescent girls compared to RT alone. These results highlight the potential of CT programs for improving overall physical performance in this population. Full article

Background/Objectives: The purpose of this study was to investigate the effect of a short-term passive post-exercise heat acclimation (HA) protocol on anaerobic performance in college students. Methods: In total, 28 participants (age 22.3 ± 2.1 years, height 168 ± 9.1 cm, mass 71.5 ± 16.6 kg) volunteered and were randomly divided into either an intervention (INT) or control (CON) group. Both groups followed a consecutive two-day protocol, consisting of a 25 min submaximal cycle @ 50–60% heart rate reserve (HRR), followed by a 25 min hot water immersion (INT) or nothing (CON). All participants performed a 30 s Wingate Anaerobic Test (WAnT) on four separate occasions—familiarization, pre-intervention, acutely post-intervention, and 24 h post intervention. The WAnT measured their peak power (W), relative peak power (W/kg), mean power (W), fatigue index (%), and total work (kJ). Results: From the results of the Factorial ANOVA, it was found that there were no significant differences, with no main effect for group (INT vs. CON) or time (Trials 1–4) and no significant interaction across all measured variables (p > 0.05). Conclusions: A two-day post-exercise passive HA protocol utilizing hot water immersion had no significant effect on the measurement of anaerobic performance in college students. Full article

Mitochondria are crucial for cellular functioning, serving as both an intracellular energy source and a signaling organelle. Recent evidence also highlights their existence outside of cells, where they participate in cell-to-cell communication. Cardiometabolic disease (CMD) has a complex pathogenesis closely associated with mitochondrial dysregulation, inflammation, and metabolic abnormalities. This review explores the roles of circulating extracellular mitochondria (CEMI) in CMD, detailing how their various forms, whether as intact structures or within vesicles, contribute to CMD pathogenesis. We classify different forms of CEMIs and discuss their potential as biomarkers and therapeutic agents in CMDs. We also describe mitochondrial transplantation as an emerging therapy for restoring cellular function in damaged tissues. Finally, to standardize CEMI assessment, we propose the Universal CEMI Assessment Protocol (UCAP), a framework aimed at enhancing comparability and reproducibility across studies. Full article

Firefighting is a physically demanding occupation that requires optimal fitness and coordination in addition to other physical and cognitive skills. When firefighters lack the physical fitness necessary to perform their duties, they put themselves and others in danger of injury and even death. The heavy, unbreathable personal protective equipment worn to shield firefighters from harmful conditions also promotes overall performance decrements via restricted range of motion as well as energy expenditure and heat-related fatigue. Firefighters are expected to carry other heavy loads, such as hose packs, tools, and victims, while working in hazardous environments. In addition to external load carriage, many firefighters also carry excess body fat that may contribute to poor physical fitness and performance. Therefore, it is imperative to incorporate training strategies to optimize load carriage and improve body composition for improved physical performance during emergencies. Thus, the aims of this narrative review are to (1) explore the impact of firefighter-specific issues on physical performance and safety and (2) identify strategies to assess and optimize occupational performance and safety. Plyometrics; resistance training; and exercise selection, volume, and intensity specifically for improving physical performance in firefighters will be discussed. Full article

Marathon sports events and those who participate in them have grown over the last years, reflecting notably an augmentation of women and master runners’ participation. The aim of the present narrative review was to briefly present the results of studies on anthropometric, physiological, and training characteristics, as well as predictors of performance, in marathon runners. It was observed that performance was better in runners with a small body weight, body mass index, body fat percentage, and rate of endomorphy. Regarding physiology, an increased maximal oxygen uptake, anaerobic threshold, and improved running economy could result in a faster race time. The training variables that could predict performance involved weekly training volume (distance) and intensity (running speed), as well as history of training (years). A combination of these three broad categories of characteristics may offer an approximate estimation of the race speed considering that other aspects (e.g., nutrition, biomechanics, and motivation) influence race performance, too. In summary, the findings of the present study provided an overview of the anthropometric, physiological, and training characteristics associated with marathon race times; thus, optimization of any of these characteristics would be expected to improve the race time. Full article

This study describes the relationships between different physiological measurements and combinations of critical velocity and performance in elite open-water swimmers. A total of 15 international male open-water swimmers performed a 5 × 200 m front crawl incremental test to estimate maximal aerobic speed (MAS), maximal oxygen consumption (VO2_max), the first lactate threshold (VLT1), the second lactate threshold (VLT2), the speed corresponding to 2 mmol/L (V_2mmol/L) and to 4 mmol/L (V_4mmol/L), and the lactate threshold (V_Dmax). A 10 km pool trial was also performed to assess swimming performance. Official competition performances in 200, 400, 800, and 1500 m events were collected and were also used to calculate critical velocity (CV) with various combinations of distances. Personal best performances in 1500 m events were 941.76 ± 20.28 s. For the 10 km trial, performance was strongly correlated to V_LT1 and moderately to V_2mmol/L (r = 0.73 and 0.67, respectively). For the 400, 800, and 1500 m events, strong correlations were observed for V_2mmol/L and V_4mmol/L. Moderate correlations with these events were also observed for V_LT1 and for V_Dmax (400 and 800 m only). For long-distance swimmers, assessment with a fixed blood lactate value seems to be a good option to estimate swimming performance in distance events. In addition, 10 km performance seems to be more related to the aerobic threshold than the anaerobic threshold. Full article

Background: We tested whether gene polymorphisms for angiotensin-converting enzyme (ACE, rs1799752) and tenascin-C (TNC, rs2104772) are associated with variability in fatigue resistance and metabolic strain during static lumbar exercise through interactions with chronic nonspecific lower back pain and habitual physical exercise levels (PA). Methods: Forty-eight patients and matched controls performed an isometric endurance test for lumbar extensors. Metabolic strain to longissimus muscle (oxygen saturation, lactate) and cardiovascular system (muscle hemoglobin, blood pressure) and holding time were monitored. Subjects were genotyped for rs1799752 (II, ID, DD) and rs2104772 (AA, AT, TT). Associations of variance with group, genotype, and PA were analyzed under a 5% false discovery rate. Results: The holding time was lower in patients than in controls (150.9 vs. 188.6 s). This difference was associated with both genotypes, as patients with DD-rs1799752-genotype (p = 0.007) and TT-rs2104772-genotype (p = 0.041) showed lower fatigue resistance. Muscle deoxygenation during exercise varied in positive association with the rs2104772-genotype and PA (p = 0.010, η2 = 0.236). Mean arterial blood pressure (p = 0.028, η2 = 0.108) and recovery of hemoglobin concentration (p = 0.003, η2 = 0.907) demonstrated complex group x rs2104772 interactions. Conclusions: Polymorphisms rs1799752 and rs2104772 influence back pain-related variability in lumbar fatigue resistance. rs2104772 was linked to cardiovascular strain during isometric exercise and recovery via muscle perfusion. Full article

Background: Menopause is a significant period in the life of a female; many hormonal and lifestyle changes occur, which can have a catastrophic effect on their health and well-being. Amongst these changes is the loss of muscle mass and strength. Resistance training is recommended for post-menopausal women; however, the role of protein in muscle mass and strength in this population is unclear. Methods: This narrative review discusses the research evidence regarding daily protein needs, dose and timings of intake, and protein quality. Results: Observational and interventional studies suggest post-menopausal females should ingest at least the RDA 0.8 g·kg⁻¹·d⁻¹ of protein, the dosing at each meal maybe important. Both whey and soy protein may provide some benefit to muscle strength. Conclusions: Overall, there is limited evidence and not of high quality, making it difficult to make inferences about the protein needs of post-menopausal females. Full article

Researchers have hypothesized that high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MOD) lead to different patterns of shear stress in the brachial artery. These differing patterns of shear stress are thought to partially explain the differing chronic adaptations to these two types of exercise. No study has directly compared blood flow characteristics during HIIE and MOD. Sixteen healthy males (Age: 23 ± 3 years) completed two randomly assigned exercise visits: HIIE (10 × 1 min intervals at 90–95% of HR_max with 1 min of recovery between) or MOD (30 min at 70% of HR_max) on an electronically braked cycle ergometer. Brachial artery blood flow velocity and diameter were measured for a total of 12 min during each of the exercise sessions. Both anterograde blood flow (MOD: 191.3 ± 80.3 mL/min, HIIE: 153.9 ± 67.5 mL/min, p = 0.03) and shear rate (MOD: 203.5 ± 78.1 s⁻¹, HIIE: 170.8 ± 55.5 s⁻¹, p = 0.04) were higher during MOD compared to HIIE. Both retrograde blood flow (MOD: −48.7 ± 21.3 mL/min, HIIE: −63.9 ± 23.3 cm/s, p < 0.01) and shear rate (MOD: −51.5 ± 19.8 s⁻¹, HIIE: −73.8 ± 28.4 s⁻¹, p < 0.01) were of greater magnitude during HIIE compared to MOD. During exercise, brachial artery diameter (p = 0.34) did not differ between HIIE and MOD. Continuous moderate cycling exercise leads to higher brachial artery anterograde shear rate and blood flow, but lower retrograde shear rate and blood flow when compared to high-intensity interval exercise. These differences during exercise in blood flow characteristics could shed light on the differing chronic adaptations to these two types of exercise. Full article

Citrulline malate (CM) has been touted as a nutritional ergogenic aid for sports performance, with purported mechanisms of increased muscle blood flow, ammonia clearance, and adenosine triphosphate resynthesis. Combined, these physiological benefits may be best applied to whole-body endurance exercises, such as swimming, though this postulate has not yet been explored. In a double-blind, randomised, and crossover design, 11 national-level swimmers (age: 17 ± 3 years, height: 1.71 ± 0.05 m, body mass: 60.6 ± 8.3 kg) from a high-performance swimming club ingested either 15 g CM or a placebo (PLA) 60 min before six × 300 m freestyle bouts (at 4.5 min intervals). Blood lactate, blood pressure, and ratings of perceived exertion were measured at baseline, 60 min post-ingestion, and immediately post-exercise. Neither mean 300 m swimming time (CM: 212.0 ± 9.6 vs. PLA: 212.8 ± 7.7 s, p = 0.683, g = 0.09) nor any individual swimming bouts (p = 0.679, Pŋ² = 0.02) were improved with CM ingestion. Moreover, no differences in any physiological or subjective measures were identified between conditions (all p > 0.05). Whether the proposed CM mechanisms were active was unclear as more direct physiological measures (i.e., plasma NO, ammonia) may have been required. Resultantly, these observations do not support an ergogenic effect of acute CM ingestion in highly trained swimmers. Full article

Recommendations for endurance exercise prescription are often based on percentages of heart rate (HR) or the volume of oxygen consumption ($\dot{\mathrm{V}}$O₂) maximum or reserve that is extrapolated to a power output (P) or velocity. Previous work has demonstrated dissociations of the expected responses to exercise anchored to the critical heart rate (CHR) compared with the P associated with CHR. However, it is unclear if similar dissociations due to reductions in P to maintain the designated intensity would be present during exercise anchored to the $\dot{\mathrm{V}}$O₂ associated with CHR ($\dot{\mathrm{V}}$O₂CHR). The purpose of this study was to examine the patterns in physiological ($\dot{\mathrm{V}}$O₂, HR, P, respiration rate [RR], muscle oxygen saturation [%SmO₂]), neuromuscular (electromyographic and mechanomyographic amplitude [EMG AMP, MMG AMP], mean power frequency [EMG MPF, MMG MPF]), and perceptual (rating of perceived exertion [RPE]) responses during exercise at $\dot{\mathrm{V}}$O₂CHR ($\dot{\mathrm{V}}$O₂-clamp). On separate days, ten participants (age: 25 ± 4 yr) performed a graded exercise test and four constant P trials at 85–100% of peak P (PP) to derive CHR and $\dot{\mathrm{V}}$O₂CHR. Responses were recorded during a trial to exhaustion at $\dot{\mathrm{V}}$O₂CHR (32.86 ± 7.12 mL·kg⁻¹·min⁻¹; T_Lim = 31.31 ± 21.37 min) and normalized in 10% intervals of T_Lim to their respective values at PP. The one-way repeated-measures ANOVA with post hoc, Bonferroni-corrected, pairwise comparisons indicated differences (p < 0.001) from baseline for HR (mean ± SD %change = 8 ± 3%), RR (43 ± 38%), P (−15 ± 5%), EMG MPF (10 ± 8%), and RPE (65 ± 38%), but no differences (p = 0.077–0.955) for %SmO₂ (−17 ± 53%), EMG AMP (−3 ± 16%), MMG AMP (40 ± 61%), and MMG MPF (1 ± 7%). The loss in performance observed during $\dot{\mathrm{V}}$O₂-Clamp exercise may provide a quantification of the inefficiency associated with the $\dot{\mathrm{V}}$O₂ slow component phenomenon. The neuromuscular responses suggested constant muscle excitation despite the reductions in P, but the metabolic and perceptual responses suggested a combination of feedforward and feedback mechanisms regulating T_Lim. Future studies should further examine responses to the $\dot{\mathrm{V}}$O₂-Clamp exercise at a uniform threshold. Full article