ECSS Paris 2023: CP-AP17
INTRODUCTION: Acute resistance training performance is influenced by daily internal load fluctuations. Training individualisation and auto-regulation adjust external load according to internal load variations to optimise performance and manage fatigue, though evidence of their superiority over linear progression for strength and hypertrophy is inconsistent. Furthermore, limited research has examined which internal load markers are most strongly associated with acute external load performance. Therefore, this study examined the relationship between daily internal load variations and external load during resistance training. METHODS: Eight resistance-trained healthy participants (4 F; age 36.4 ± 11.7 y; training experience 15.3 ± 10.1 y) completed a 4-week single-group protocol including 1RM testing, six resistance training sessions, and 1RM re-testing with ≥ 48 h between sessions. Training was performed twice per week for three weeks at 80% 1RM for the leg extension, leg curl, chest press, arm extension, low row and arm curl, with three sets to muscular failure per exercise and 2-min rest intervals. Exercises were paired and their order was counterbalanced across sessions. Before each session, psychophysiological status was assessed via questionnaires (EES, FFS–Fatigue, SQS, PRS, VAS-DOMS) and neuromuscular measures (BIA, handgrip strength, Ruffier test, isokinetic tests). Post-session assessments included physical and mental session RPE, FFS–Fatiguability, EES, and repeated neuromuscular measures. RESULTS: Two separate linear regression models were conducted. In the first model, the fatiguability sub-scale was included as the dependent variable, while psycho-physiological measures and load-related indices were independent variables. Session physical RPE was positively associated with fatiguability. Conversely, physical sRPE-to-tonnage ratio was negatively associated with fatiguability. In the second model, session mental and physical RPE were included as independent variables, psycho-motivational variables and external load were included as dependent variables. Tonnage was positively associated with both session mental and physical RPE. Additionally, sleep quality was negatively associated with session mental RPE. No further significant relationships were detected in both analysis. CONCLUSION: The present findings indicate a consistent association between external load and internal load markers during resistance training. Greater training volume was accompanied by higher perceived mental and physical fatigue, supporting the relationship between mechanical demand and subjective load. Physical RPE was associated with post-session fatiguability, suggesting that perceived exertion reflects acute fatigue. The association between poor sleep quality and higher mental fatigue highlights the contribution of non-training-related internal load factors to perceived session demands. Results should be interpreted cautiously due to the small sample size, short intervention and preclude causal inference.
Read CV Alessandro BracciECSS Paris 2023: CP-AP17
INTRODUCTION: Sleep is a critical factor for neuromuscular recovery and optimal physical performance, and sleep deprivation has been shown to increase perceived exertion and accelerate exhaustion during high-intensity exercise. However, the extent to which sleep deprivation contributes to central and peripheral fatigue remains unclear. Therefore, this study aimed to investigate the effects of acute sleep deprivation on hamstring and quadriceps muscle fatigue during eccentric exercise. METHODS: A total of 19 recreationally active participants (9 males and 10 females; mean ± SD age: 21.05 ± 1.46 years; body mass: 21.99 ± 2.89 kg) with good sleep quality, determined using the Pittsburgh Sleep Quality Index and a 5-point Likert scale, were recruited for this randomized crossover study. Each participant completed two experimental sessions separated by a 2-week washout period. The first session was conducted 2 hours after awakening under habitual sleep conditions. The second session was performed at the same time of day following 24 hours of total sleep deprivation. The testing protocol consisted of a Maximum Voluntary Isometric Contraction (MVIC) for normalization purposes, followed by an isokinetic eccentric exercise protocol. The amount of fatigue in the hamstring and quadriceps muscle groups during 15 repetitions of isokinetic eccentric contraction was determined using the slope value (slope coefficient) of muscle activation in normal sleep and sleep deprivation conditions. The obtained data were analyzed using the dependent groups t-test. RESULTS: The amount of fatigue occurring in the RF muscle as a result of 15 repetitions of eccentric contraction was statistically higher after sleep deprivation intervention compared to normal sleep (p=0.018). There was no statistically significant difference in fatigue between normal sleep and sleep deprivation conditions in the VM, VL, BF, and ST muscles (p>0.05). CONCLUSION: This study showed that 24 hours of total sleep deprivation significantly increased fatigue in the rectus femoris muscle during repeated eccentric contractions, while no significant differences were observed in the other hamstring and quadriceps muscles. These findings suggest that sleep deprivation may have muscle-specific effects rather than causing a generalized increase in lower extremity fatigue. Therefore, acute sleep loss may negatively influence certain aspects of neuromuscular performance.
Read CV sonay guruhanECSS Paris 2023: CP-AP17
INTRODUCTION: Performance fatigability is a multifactorial construct involving interacting neuromuscular, perceptual, and autonomic mechanisms that determine exercise tolerance (1, 2). Reductions in fractal correlation properties of heart rate variability measured by the short-term exponent of detrended fluctuation analysis (DFAα1) have been proposed as a promising marker of durability during exercise near maximal metabolic steady state (MMSS) (2). However, whether changes in DFAα1 are associated with the neuromuscular and perceptual components of fatigability at this intensity remains unclear. Therefore, this study investigated whether reductions in DFAα1 are associated with neuromuscular performance fatigability and perceptual responses when exercising near the MMSS. METHODS: Sixteen healthy participants (8 males, 8 females) completed two sessions: 1) A cycling step-ramp-step test to determine the ramp-corrected power output at the respiratory compensation point (estimation of MMSS); 2) a constant-load ride at 95% of MMSS until task failure (TF). During session 2, neuromuscular performance fatigability was assessed at baseline (BL), after 7.5 min of exercise, and at TF using maximal voluntary contractions combined with supramaximal peripheral electrical stimulation. Voluntary activation (VA%) was estimated using the twitch interpolated technique, and peripheral function was assessed via potentiated twitch force (Tw). Ratings of perceived exertion (RPE) and DFAα1 were assessed at the same time points. Repeated-measures ANOVA with Bonferroni post hoc assessed within-exercise changes. Pearson correlations assessed associations between absolute changes in DFAα1 and corresponding changes in neuromuscular and RPE from BL to 7.5 min and from BL to TF. Significance was set at p< 0.05. RESULTS: Time to TF was 44.6 ± 9.6 min. VA% decreased at 7.5 min and further at TF (Δ from BL: −3.1 ± 2.9% and −7.8 ± 3.3%, respectively; p≤ 0.03). Tw force declined progressively at 7.5 min and TF (Δ from BL: −39.5 ± 14.1% and −52.4 ± 15.7%, respectively; p< 0.01). RPE responses increased from BL to 7.5 min and further at TF (7 ± 1, 12 ± 2, and 16 ± 3 a.u., respectively; p< 0.01). DFAα1 decreased across the same time points (1.39 ± 0.16, 0.86 ± 0.24, and 0.60 ± 0.27, respectively; p< 0.01). No associations were found between changes in DFAα1 and neuromuscular or RPE responses from BL to 7.5 min. However, absolute reductions in DFAα1 from BL to TF were associated with increase in RPE over the same period (r= −0.68; p< 0.01), with no association with neuromuscular performance fatigability. CONCLUSION: Reductions in DFAα1 from BL to TF were associated with increases in RPE, whereas no associations were observed with neuromuscular fatigability responses. These findings suggest that reductions in DFAα1 are more closely related to the perceptual dimension of exercise fatigability than to neuromuscular impairment. (1) Iannetta et al 2022, JAP, 133(2),323–34/ (2) Rogers et al 2025, EJAP, 125(6),1619–31
Read CV Rodrigo de PoliECSS Paris 2023: CP-AP17