Ischemic Preconditioning (IPC) Enhances the Accuracy and Stability of Proprioception

Abstract

This study aimed to investigate the differences in proprioceptive changes at different time points (Pre vs. Post vs. 90 min vs. 24 h) before and after ischemic preconditioning. It followed a within-subject, self-controlled design, and a total of 21 trained male participants were assessed using two-point discrimination threshold tests on thigh and knee joint position sense testing. The results demonstrated that ischemic preconditioning effectively improved proprioceptive accuracy (two-point discrimination, right lower limb, p < 0.001; two-point discrimination, left lower limb, p < 0.001; knee position sense, right lower limb, p = 0.001; knee position sense, left lower limb, p = 0.014) and stability (two-point discrimination, right lower limb, p < 0.001; two-point discrimination, left lower limb, p = 0.002; knee position sense, right lower limb, p < 0.001; knee position sense, left lower limb, p = 0.003), with the optimal time point for enhancement identified at 90 min. This research suggests administering IPC 90 min before warm-up or competition to enhance athletic performance.

1. Introduction

Proprioception plays a pivotal role in the execution of movement processes. The coordination, balance, and rapid response perceptions during physical activity heavily rely upon proprioceptive input [1]. Within the realm of movement, the human body is reliant upon proprioceptive feedback [2]. Only when sensory receptors convey accurate information to the central nervous system can the organism execute corresponding actions and subsequently perceive position, enabling the central nervous system to facilitate posture control and adjustment. Impairments within the proprioceptive system can lead to delays or inaccuracies in information transmission, consequently instigating disruptions in position perception, thereby impeding posture control and movement performance and resulting in adverse effects on bodily control [3]. The proper functioning of the proprioceptive system holds paramount importance in eliciting responsive and coordinated actions amidst bodily movements [4].

Ischemic preconditioning represents a non-invasive approach for acute skill enhancement [5]. It involves the transient induction of circulatory ischemia and subsequent reperfusion in the limbs through the application of pressure cuffs prior to physical activity. This preconditioning procedure elicits a hypoxic stress response, stimulating the secretion of protective factors like adenosine and kinins [6], thereby facilitating local vasodilation, optimizing blood flow distribution, enhancing oxygen delivery, and ultimately augmenting exercise performance [7].

Ischemic preconditioning (IPC) has garnered increasing attention within the field of exercise science. Current research on the effects of IPC primarily focuses on changes in strength, power, and endurance. Previous studies indicate that IPC can enhance not only power output, maximal muscular strength, and anaerobic endurance but also improve subjects’ aerobic capacity and fatigue resistance [8]. The ergogenic mechanisms of IPC likely involve modulating vasoregulatory effects, attenuating perceptions of fatigue or pain during exercise, and transiently enhancing skeletal muscle metabolic efficiency [9,10].

While the role of IPC in enhancing exercise performance is receiving growing research interest, investigations have predominantly concentrated on its impacts on strength, power, and endurance, overlooking potential alterations in proprioception. However, muscular coordination and coordinated neuromuscular signaling rely heavily on proprioceptive input [8]. Changes in proprioception are crucial for the quality of movement execution and the feedback necessary for movement adjustments [1,2,3,4]. In many sports, athletes cannot rely solely on visual feedback to adjust their movements during competition or training in real time; these adjustments primarily depend on proprioceptive feedback. Athletes possessing superior proprioceptive acuity would benefit during movement adjustment processes, leading to more precise movements and, ultimately, enhanced athletic performance.

Currently, no research has investigated the potential influence of IPC on proprioception. Given the known physiological mechanisms through which IPC induces changes in the human body, IPC may enhance proprioception through neuromodulatory pathways. However, whether IPC indeed affects proprioception, and the optimal time window for any such effect, remain entirely unknown. While no studies have yet investigated the effects of IPC on proprioception, this does not diminish the potential research significance of this topic. In athletic practice, prolonged activities requiring fine motor control—such as basketball shooting and baseball pitching—demand high levels of proprioceptive precision and stability. Should research demonstrate that IPC can effectively enhance the precision and stability of an athlete’s proprioception at specific time points, this could yield a potentially positive impact on competitive performance.

This study examined the temporal dynamics of proprioception relative to IPC application across four timepoints: pre-IPC, and 0 min, 90 min, and 24 h post-IPC. The objectives were to determine whether IPC influences proprioception and to identify the optimal time frame for any observed effect. This study hypothesizes that IPC may improve proprioceptive stability and precision. Peak effectiveness in both stability and precision is anticipated to occur at one of the following time points: immediately after IPC intervention, at 90 min post-intervention, or at 24 h post-intervention.

2. Materials and Methods

2.1. Participants

The sample size was determined using G*power (3.1, Kiel University, Kiel, Germany) with the following parameters: input effect size f = 0.5; α err prob = 0.05; Power (1-β err prob) = 0.95; achieved power = 0.87. The minimum sample size required was 10 individuals, and 21 male participants (n = 19, age: 22.8 ± 2.2 years; height: 179.9 ± 5.5 cm; mass: 79.8 ± 7.8 kg) were ultimately included with two dropouts. All participants were undergraduate students majoring in sport training at Beijing Sport University, possessing a solid background in both athletics and strength training. Participants were required to meet strict inclusion criteria, which included being physically active, while also satisfying exclusion criteria, such as having absolute or relative contraindications to the study protocols; recent joint surgery; use of prostheses, orthoses, or assistive devices; chronic heart, lung, or skin conditions. Other inclusion criteria included an absence of physical disabilities, adequate cognitive abilities to understand the test protocols, and independence in performing activities of daily living. The study was conducted in accordance with the Declaration of Helsinki and approved by the Sports Science Experiment Ethics Committee of Beijing Sport University (approval no. 2025125H).

2.2. Design

Participants underwent pre-testing followed by ischemic preconditioning. After the completion of ischemic preconditioning, participants underwent post-testing at three time points (immediately, 90 min, and 24 h after the completion of ischemic preconditioning) (Figure 1).

2.3. Ischemic Preconditioning

The ischemic preconditioning protocol involved rapidly inflating a blood pressure cuff (Technogym international trading Ltd., Cesena, Italy) positioned at the top of the thigh. In the ischemic preconditioning condition, the cuff was inflated to 220 Hg for three 5 min periods, with 5 min rest/reperfusion intervals [11].

2.4. Two-Point Discrimination Test

The measurements were conducted using a DL90150 electronic caliper (Deli Technology Co., Ltd., Ningbo, China) with a range of 0–130 mm and an accuracy of 0.01 mm. Participants were seated with their eyes closed. For the two-point discrimination test of the lower limbs, the examiner placed the probes vertically on the anterior side of the thigh at the midpoint of the rectus femoris belly. Equal pressure was applied for two seconds, and participants immediately reported whether they felt one or two points of stimuli. If participants could not differentiate or only felt one stimulus, the minimum distance between two stimuli was recorded [12,13]. The entire testing process was performed by a single examiner for consistency. The interval between stimuli was more than five seconds, and the measurement was repeated three times. The collected data was used to calculate the average, representing the participant’s two-point discrimination threshold accuracy, and the variance, reflecting the stability of their threshold.

$${\mathrm{Accuracy}}_{\mathrm{TPD}}=(Tria{l}_1+Tria{l}_2+Tria{l}_3)/3$$

(1)

$${\mathrm{Stability}}_{\mathrm{TPD}}={\displaystyle \frac{{(Tria{l}_1-m)}^2+{(Tria{l}_2-m)}^2+{(Tria{l}_3-m)}^3}{3}}$$

(2)

m: mean; TPD: two-point discrimination.

2.5. Knee Position Sense Test

The measurements were performed using a Syntek electronic joint angle measurement device (Deqingshengtaixin Technology Co., Ltd., Deqing, China), which has a range of 0–180°, a resolution of 0.1°, and an accuracy of ±0.3°. Participants were instructed to lie supine with their eyes closed, knees flexed at 90°, and hips flexed at 90°, supported by a surface. The examiner positioned the goniometer with its center at the tibial tuberosity, one side aligned with the line connecting the tibial tuberosity and the greater trochanter of the femur, and the other side aligned with the line connecting the tibial tuberosity and the lateral malleolus. Participants were then asked to lift their lower leg at 40° without making adjustments during the process (Figure 2). Measurements were taken once the knee joint angle stabilized. The examiner repeated the measurement three times, with an interval of over five seconds between each measurement [14,15]. The entire testing process was conducted by the same examiner to ensure consistency, with the examiner remaining silent to avoid providing verbal feedback that could influence the results. The collected data was used to calculate the average, reflecting the accuracy of the participant’s knee position sense, and the variance, reflecting the stability of their knee position sense.

Figure 2. Knee position sense test.

Figure 2. Knee position sense test.

$${\mathrm{Accuracy}}_{KPS}={\displaystyle \frac{(TP-Tria{l}_1)+(TP-Tria{l}_2)+(TP-Tria{l}_3)}{3}}$$

(3)

$${\mathrm{Stability}}_{KPS}={\displaystyle \frac{{(TP-Tria{l}_1-m)}^2+{(TP-Tria{l}_2-m)}^2+{(TP-Tria{l}_3-m)}^2}{3}}$$

(4)

TP: target position; m: mean.

2.6. Statistical Analyses

The study data were analyzed using SPSS software (version 26; SPSS, IBM Corporation, Armonk, New York, NY, USA) and WPS software (version 2023; Kingsoft Office Co., Ltd., Beijing, China). All variables are presented as means and standard deviations (SDs). The data were tested for the assumption of sphericity. If the assumption was violated, the Greenhouse–Geisser correction coefficient was applied to adjust the degrees of freedom for the relevant mean squares, ensuring the reliability of the analysis of variance. A one-way repeated-measures analysis of variance (ANOVA) was conducted to examine the changes in body perception at different time points (Pre vs. Post vs. 90 min vs. 24 h) among participants. A confidence interval of 95% was utilized. Based on Cohen’s conventions [16], the effect sizes reported as Cohen’s d (small: d = 0.2, medium: d = 0.5, large: d = 0.8).

3. Results

The experimental results indicate that there are significant differences (p < 0.05) in the accuracy and stability of two-point discrimination thresholds and knee joint position sense across different time points (Pre vs. Post vs. 90 min vs. 24 h) (

Table 1. Descriptive statistics. TPDR: two-point discrimination threshold on right lower limb; TPDL: two-point discrimination threshold on left lower limb; D40R: difference in position sense test of right lower limb; D40L: difference in position sense test of left lower limb.

		Accuracy	Stability
		Mean ± SD	Mean ± SD
Pre	TPDR	56.28 ± 13.32	14.31 ± 9.89
	TPDL	56.08 ± 12.86	14.49 ± 11.95
	D40R	−6.21 ± 10.06	14.55 ± 11.18
	D40L	−7.38 ± 8.71	10.11 ± 7.07
Post	TPDR	47.56 ± 8.02	7.87 ± 5.22
	TPDL	45.55 ± 10.15	7.93 ± 5.54
	D40R	0.22 ± 7.87	6.98 ± 5.80
	D40L	−2.73 ± 6.49	6.36 ± 6.83
90 min	TPDR	39.82 ± 6.63	2.55 ± 2.92
	TPDL	39.20 ± 7.00	2.45 ± 1.60
	D40R	0.49 ± 3.51	2.06 ± 1.72
	D40L	−1.55 ± 2.96	1.72 ± 2.02
24 h	TPDR	49.62 ± 9.02	11.88 ± 7.03
	TPDL	48.26 ± 8.51	9.22 ± 6.64
	D40R	−1.55 ± 2.96	8.78 ± 7.72
	D40L	−1.29 ± 9.09	8.99 ± 6.87

and

Table 2. Results of one-way repeated ANOVA. TPDR: two-point discrimination threshold on right lower limb; TPDL: two-point discrimination threshold on left lower limb; D40R: difference in position sense test of right lower limb; D40L: difference in position sense test of left lower limb. Mauchly’s test of sphericity indicated violations for AccuracyTPDR, AccuracyD40L, StabilityTPDR, StabilityTPDL, StabilityD40R, and StabilityD40L. Consequently, Greenhouse–Geisser corrections were applied to these measures.

Source		df	Mean Square	F	p	Partial Eta Squared
Accuracy	TPDR	2.011	1304.199	27.168	<0.001	0.601
	TPDL	3.000	930.075	28.154	<0.001	0.610
	D40R	3.000	183.726	6.259	0.001	0.258
	D40L	2.033	192.183	4.806	0.014	0.211
Stability	TPDR	2.175	693.134	11.586	<0.001	0.392
	TPDL	1.555	892.681	9.117	0.002	0.336
	D40R	2.187	694.108	11.027	<0.001	0.380
	D40L	2.001	395.699	7.064	0.003	0.282

). Partial eta-squared values indicated large effect size across all significant comparisons (η² > 0.14, 95% CI).

In pairwise comparisons of proprioceptive accuracy, significant differences were observed for TPDR between Pre and Post (p = 0.002), Pre and 90 min (p < 0.001), and Pre and 24 h (p = 0.002); Post and 90 min (p < 0.001) and Post and 24 h (p < 0.001); and 90 min and 24 h (p < 0.001). For TPDL, significant differences occurred between Pre and Post (p = 0.001), Pre and 90 min (p < 0.001), Pre and 24 h (p = 0.023); Post and 90 min (p = 0.004); and 90 min and 24 h (p < 0.001). For D40R, significant differences were found between Pre and Post (p = 0.002) and Pre and 90 min (p = 0.016). For D40L, a significant difference was detected between Pre and Post (p = 0.035) (

Table 3. The results of paired comparisons of the accuracy of proprioception. TPDR: two-point discrimination threshold on right lower limb; TPDL: two-point discrimination threshold on left lower limb; D40R: difference in position sense test of right lower limb; D40L: difference in position sense test of left lower limb. Based on estimated marginal means, the significance level (“*”) for mean differences was set at 0.05, with multiplicity adjustment via the Bonferroni method.

Measurement	(I) Time	(J) Time	Error of the Mean (I–J)	SD	p	CI, 95%
						Lower	Upper
TPDR	Pre	Post	8.726 *	1.978	0.002	2.866	14.587
		90 min	16.468 *	2.498	<0.001	9.068	23.869
		24 h	6.663 *	1.928	0.017	0.952	12.374
	Post	Pre	−8.726 *	1.978	0.002	−14.587	−2.866
		90 min	7.742 *	1.402	<0.001	3.589	11.895
		24 h	−2.063	1.634	1.000	−6.903	2.777
	90 min	Pre	−16.468 *	2.498	<0.001	−23.869	−9.068
		Post	−7.742 *	1.402	<0.001	−11.895	−3.589
		24 h	−9.805 *	1.349	<0.001	−13.802	−5.808
	24 h	Pre	−6.663 *	1.928	0.017	−12.374	−0.952
		Post	2.063	1.634	1.000	−2.777	6.903
		90 min	9.805 *	1.349	<0.001	5.808	13.802
TPDL	Pre	Post	10.537 *	2.130	0.001	4.227	16.846
		90 min	16.889 *	2.088	<0.001	10.702	23.077
		24 h	7.821 *	2.353	0.023	0.849	14.793
	Post	Pre	−10.537 *	2.130	0.001	−16.846	−4.227
		90 min	6.353 *	1.562	0.004	1.726	10.979
		24 h	−2.716	1.620	0.666	−7.516	2.085
	90 min	Pre	−16.889 *	2.088	<0.001	−23.077	−10.702
		Post	−6.353 *	1.562	0.004	−10.979	−1.726
		24 h	−9.068 *	1.169	<0.001	−12.532	−5.605
	24 h	Pre	−7.821 *	2.353	0.023	−14.793	−0.849
		Post	2.716	1.620	0.666	−2.085	7.516
		90 min	9.068 *	1.169	<0.001	5.605	12.532
D40R	Pre	Post	−6.437 *	1.423	0.002	−10.654	−2.220
		90 min	−6.700 *	1.930	0.016	−12.418	−0.982
		24 h	−4.911	1.985	0.141	−10.791	0.970
	Post	Pre	6.437 *	1.423	0.002	2.220	10.654
		90 min	−0.263	1.360	1.000	−4.293	3.766
		24 h	1.526	1.824	1.000	−3.879	6.932
	90 min	Pre	6.700 *	1.930	0.016	0.982	12.418
		Post	0.263	1.360	1.000	−3.766	4.293
		24 h	1.789	1.916	1.000	−3.887	7.465
	24 h	Pre	4.911	1.985	0.141	−0.970	10.791
		Post	−1.526	1.824	1.000	−6.932	3.879
		90 min	−1.789	1.916	1.000	−7.465	3.887
D40L	Pre	Post	−4.663 *	1.490	0.035	−9.077	−0.249
		90 min	−5.832	2.282	0.119	−12.593	0.930
		24 h	−2.074	1.300	0.768	−5.924	1.776
	Post	Pre	4.663 *	1.490	0.035	0.249	9.077
		90 min	−1.168	1.501	1.000	−5.615	3.278
		24 h	2.589	1.473	0.574	−1.773	6.952
	90 min	Pre	5.832	2.282	0.119	−0.930	12.593
		Post	1.168	1.501	1.000	−3.278	5.615
		24 h	3.758	1.891	0.374	−1.845	9.361
	24 h	Pre	2.074	1.300	0.768	−1.776	5.924
		Post	−2.589	1.473	0.574	−6.952	1.773
		90 min	−3.758	1.891	0.374	−9.361	1.845

).

In pairwise comparisons of proprioceptive stability, significant differences were observed: For TPDR: between Pre and 90 min (p < 0.001), Post and 90 min (p = 0.010), and 90 min and 24 h (p < 0.001). For TPDL: between Pre and 90 min (p = 0.003), Post and 90 min (p = 0.002), and 90 min and 24 h (p = 0.003). For D40R: between Pre and 90 min (p < 0.001), Post and 90 min (p = 0.006), and 90 min and 24 h (p = 0.009). For D40L: between Pre and 90 min (p = 0.001) and 90 min and 24 h (p = 0.003) (

Table 4. The results of paired comparisons of the stability of proprioception. TPDR: two-point discrimination threshold on right lower limb; TPDL: two-point discrimination threshold on left lower limb; D40R: difference in position sense test of right lower limb; D40L: difference in position sense test of left lower limb. Based on estimated marginal means, the significance level (“*”) for mean differences was set at 0.05, with multiplicity adjustment via the Bonferroni method.

Measurement	(I) Time	(J) Time	Error of the Mean (I−J)	SD	p	CI, 95%
						Lower	Upper
TPDR	Pre	Post	6.442	2.749	0.185	−1.701	14.586
		90 min	11.763 *	2.056	<0.001	5.671	17.856
		24 h	2.426	2.452	1.000	−4.838	9.690
	Post	Pre	−6.442	2.749	0.185	−14.586	1.701
		90 min	5.321 *	1.442	0.010	1.049	9.593
		24 h	−4.016	2.284	0.574	−10.783	2.752
	90 min	Pre	−11.763 *	2.056	<0.001	−17.856	−5.671
		Post	−5.321 *	1.442	0.010	−9.593	−1.049
		24 h	−9.337 *	1.517	<0.001	−13.833	−4.841
	24 h	Pre	−2.426	2.452	1.000	−9.690	4.838
		Post	4.016	2.284	0.574	−2.752	10.783
		90 min	9.337 *	1.517	<0.001	4.841	13.833
TPDL	Pre	Post	6.526	3.323	0.391	−3.318	16.370
		90 min	12.021 *	2.814	0.003	3.684	20.359
		24 h	5.253	2.094	0.132	−0.953	11.458
	Post	Pre	−6.526	3.323	0.391	−16.370	3.318
		90 min	5.495 *	1.252	0.002	1.786	9.203
		24 h	−1.274	2.133	1.000	−7.593	5.045
	90 min	Pre	−12.021 *	2.814	0.003	−20.359	−3.684
		Post	−5.495 *	1.252	0.002	−9.203	−1.786
		24 h	−6.768 *	1.613	0.003	−11.546	−1.990
	24 h	Pre	−5.253	2.094	0.132	−11.458	0.953
		Post	1.274	2.133	1.000	−5.045	7.593
		90 min	6.768 *	1.613	0.003	1.990	11.546
D40R	Pre	Post	7.574	2.683	0.068	−0.374	15.521
		90 min	12.500 *	2.465	<0.001	5.197	19.803
		24 h	5.784	2.373	0.152	−1.247	12.815
	Post	Pre	−7.574	2.683	0.068	−15.521	0.374
		90 min	4.926 *	1.244	0.006	1.239	8.613
		24 h	−1.789	2.295	1.000	−8.589	5.010
	90 min	Pre	−12.500 *	2.465	<0.001	−19.803	−5.197
		Post	−4.926 *	1.244	0.006	−8.613	−1.239
		24 h	−6.716 *	1.807	0.009	−12.070	−1.361
	24 h	Pre	−5.784	2.373	0.152	−12.815	1.247
		Post	1.789	2.295	1.000	−5.010	8.589
		90 min	6.716 *	1.807	0.009	1.361	12.070
D40L	Pre	Post	3.742	2.519	0.928	−3.722	11.206
		90 min	8.384 *	1.749	0.001	3.203	13.565
		24 h	1.121	2.541	1.000	−6.408	8.650
	Post	Pre	−3.742	2.519	0.928	−11.206	3.722
		90 min	4.642	1.597	0.056	−0.088	9.373
		24 h	−2.621	1.530	0.624	−7.155	1.913
	90 min	Pre	−8.384 *	1.749	0.001	−13.565	−3.203
		Post	−4.642	1.597	0.056	−9.373	0.088
		24 h	−7.263 *	1.688	0.003	−12.263	−2.263
	24 h	Pre	−1.121	2.541	1.000	−8.650	6.408
		Post	2.621	1.530	0.624	−1.913	7.155
		90 min	7.263 *	1.688	0.003	2.263	12.263

).

After ischemic preconditioning, the accuracy and stability of two-point discrimination thresholds were improved (Figure 3 and Figure 4). The greatest improvement was observed at 90 min after ischemic preconditioning. On the following day (24 h after ischemic preconditioning), the two-point discrimination thresholds remained close to the levels immediately after ischemic preconditioning. There were no significant differences observed between the left and right sides.

Following ischemic preconditioning, there was a notable enhancement in both the accuracy and stability of knee joint proprioception (Figure 5 and Figure 6). The optimal improvement was attained at the 90-min mark after ischemic preconditioning. Interestingly, even on the subsequent day (24 h after ischemic preconditioning), knee joint proprioception was able to maintain a level similar to that immediately following ischemic preconditioning, with no significant disparities observed between the left and right sides. These findings align with the outcomes observed for two-point discrimination thresholds.

4. Discussion

This study employed a self-controlled pre–post experimental design, using a single-factor repeated-measures analysis of variance (ANOVA) to examine differences in proprioception across distinct time points relative to IPC application (pre-IPC vs. immediately post-IPC vs. 90 min post-IPC vs. 24 h post-IPC). The objectives were to investigate whether IPC influences proprioception and to identify the optimal time frame for its effect. The findings demonstrate that ischemic preconditioning optimized proprioceptive accuity and precision, with the peak enhancement observed at the 90-min post-IPC time point. The findings provide a degree of theoretical support for the pre-competition implementation of IPC to optimize proprioceptive accuity and precision in sports disciplines that rely on proprioception during practical performance.

4.1. Effect of IPC on Proprioception

IPC optimizes proprioceptive accuity and precision. Previous research [7,9,10,11,17,18,19,20,21,22,23,24,25,26,27,28,29] has robustly established the ergogenic benefits of IPC for maximal strength, muscular endurance, anaerobic power output, and endurance performance. During incremental exercise tests, IPC has been shown to prolong time to exhaustion and reduce ratings of perceived exertion (RPE) [7] while concurrently enhancing maximal oxygen uptake (VO₂max), attenuating fatigue sensitivity, and improving exercise efficiency [17]. These enhancements in aerobic exercise capacity are attributed to accelerated blood flow velocity and augmented oxygen delivery [18]. Furthermore, IPC enhances maximal voluntary isometric contraction (MVIC) torque output [30] and endurance capacity [19], with peak improvements in anaerobic power typically observed between 45 and 50 min post-application [20]. However, contradictory findings regarding the impact of IPC on anaerobic capacity have generated controversy within the literature [21,22]. The findings in the present study provide stronger support for the perspective that IPC can acutely enhance anaerobic capacity. We posit that enhanced proprioceptive accuracy optimizes movement economy during anaerobic exercise execution, thereby mediating the observed acute improvement in anaerobic capacity. IPC exerts regulatory effects on target organs by stimulating autonomic and neural pathways [27]. This process involves IPC enhancing afferent neuronal excitability [28]. Additional research suggests IPC may induce the production of humoral factors such as nitric oxide (NO) and bradykinin to potentiate afferent signaling [29]. Collectively, these studies share the commonality of supporting IPC’s capacity to augment afferent neural function, offering compelling neurohumoral explanations for the improvement in proprioceptive accuracy and stability. The current study aligns with this consensus perspective. However, the primary focus of these prior investigations has been on acute performance enhancement, largely overlooking the potential contribution of altered proprioception to these acute performance gains. While the current study cannot substantiate this perspective, it proposes a novel hypothesis: IPC may achieve acute performance enhancement through improved proprioception. Subsequent investigations should prioritize exploring this proposed mechanistic pathway.

4.2. Optimal Time Frame for IPC’s Effect on Proprioception

IPC was observed to enhance proprioception at 90 min post-application. Following brief cycles of ischemia and reperfusion, IPC induces the release of substances such as adenosine and norepinephrine into the coronary effluent, ultimately entering the systemic circulation [6]. IPC-induced ischemia–reperfusion generates reactive oxygen species (ROS) that activate downstream protein kinases (e.g., protein kinase C [PKC]), subsequently opening K_ATP channels [23]. Crucially, K_ATP channel activity modulates sympathetic vasoconstriction in humans [31], thereby regulating sympathetic nervous function and ultimately enhancing proprioceptive acuity. This study hypothesizes that the mechanism underlying the enhanced proprioceptive adaptation following IPC may be analogous to these humoral mechanisms. These findings align closely with the described physiological mechanisms: the temporal delay inherent in humoral regulation likely explains why the 90-min post-IPC time window represents the peak period for proprioceptive enhancement, an effect that persisted until at least the following day. The capacity for continuous rapid motor responses during human movement fundamentally relies on intrinsic bodily signaling. Proprioceptors provide essential afferent signals regarding limb and trunk position and motion. Conscious motor control critically depends on the proprioceptive system, wherein muscle spindles, Golgi tendon organs, joint receptors, and cutaneous receptors transduce joint position, muscle length changes, and force generation. Post-exertional movement deterioration and instability stem not merely from muscular fatigue but also from degraded proprioceptive acuity in fatigued extremities and trunk. Fatigue induces not only metabolic depletion but also diminished activation at the spinal and cortical levels. This progressive proprioceptive decline during sustained exercise precipitates motor clumsiness. Prolonged muscular work induces both structural damage and proprioceptive disruption. Exercise-induced muscle soreness similarly alters proprioception via group III and IV afferent pathways [32]. Notably, ischemic preconditioning (IPC) enhances the functionality of these group III/IV afferents [24]. Proprioceptive input and output depend on signaling from muscle spindles, which primarily function through length-sensitive mechanoreceptors within group Ia and II afferent fibers [33]. Consequently, IPC may not only influence group III and IV afferents but could also exert a modulatory influence on the function of group I and II afferent fibers. The present study corroborates the aforementioned research, positing that the observed enhancement in proprioceptive accuity and precision is precisely attributable to the acute humoral regulation and sympathetic nervous adaptations induced by the transient ischemia–reperfusion stimulus inherent to IPC. Furthermore, this study addresses an aspect overlooked in prior investigations: the fundamental mechanism through which IPC enhances athletic performance (e.g., strength, speed, power output) resides in the optimization of movement economy resulting from improved proprioceptive accuity and precision.

4.3. Practical Application of IPC for Influencing Proprioception

Existing research has demonstrated that IPC intervention can enhance subsequent maximal strength levels and the number of repetitions performed at submaximal force intensities [25]. Furthermore, IPC has been shown to effectively improve anaerobic capacity [26] and aerobic capacity [24] during exercise. A limited number of studies also support an acute enhancement effect of IPC on power output and speed [9]. However, factors influencing athletic performance extend beyond strength, speed, power, and metabolic capacity; they also encompass fine motor control governed by proprioception. Indeed, the accuity and precision of such fine motor control constitute a prerequisite for the expression of other performance-related factors. The findings of the present study support the notion that IPC can improve the accuity and precision of proprioception, with this optimal effect occurring at 90 min post-IPC. Based on the findings of this study, coaching teams may consider implementing IPC approximately 90 min prior to important competitions to enhance proprioceptive function. The acute proprioceptive enhancements induced by IPC find application in specific sporting scenarios, including basketball free throws, soccer penalty kicks, and gymnastics apparatus-based routines. These proprioceptive improvements may mediate enhanced motor performance in such athletic disciplines, ultimately contributing to superior competitive outcomes. Nevertheless, whether acute improvements in sport-specific proprioception interfere with the consolidation of established motor adaptations warrants further systematic investigation. Future research should delve into these directions to refine the relevant theoretical framework.

5. Conclusions

Functioning as a non-invasive conditioning strategy, IPC effectively enhances the accuracy and stability of proprioception, with the optimal gains observed after 90 min. This study suggests that athletes can benefit from performing ischemic preconditioning 90 min before warm-up or competition to obtain improved proprioceptive feedback; such proprioceptive refinements may confer potential benefits for the enhancement of motor skills and athletic performance.

6. Limitation

This study reveals the acute effects of IPC on proprioceptive adaptation. However, the sustainability of proprioceptive optimization and the underlying adaptive mechanisms following long-term repeated IPC protocols remain poorly understood. It may be subject to placebo and learning effects; our research team will address these potential confounders in a subsequent series of investigations. As the participant cohort exclusively comprised trained male individuals, the findings may be more applicable to male athletic populations. Generalizability to other demographics (e.g., females, older adults, or other groups) remains undetermined. Future studies in this series may employ EMG/fNIRS methodologies to elucidate the mechanisms underlying IPC’s effects on proprioception.