The aim was to identify if surface electromyography (sEMG) parameters are indicative of post-activation potentiation (PAP)/post-activation performance enhancement (PAPE), in terms of twitch potentiation and voluntary performance. Three databases were used in April 2024, with the following inclusion criteria: (a) original research, assessed in healthy human adults, and (b) sEMG parameters were measured. The exclusion criteria were (a) studies with no PAP/PAPE protocol and (b) non-randomized control trials. The following data were extracted: study characteristics/demographics, PAP/PAPE protocols, sEMG parameters, twitch/performance outcomes, and study findings. A modified physiotherapy evidence database (PEDro) scale was used for quality assessment. Fifteen randomized controlled trials (RCTs), with a total of 199 subjects, were included. The M-wave amplitude (combined with a twitch torque outcome) was shown to generally be indicative of PAP. The sEMG amplitudes (in some muscles) were found to be indicative of PAPE during ballistic movements, while a small decrease in the MdF (in certain muscles) was shown to reflect PAPE. Changes in the H_max/M_max ratio were found to contribute (temporally) to PAP, while the H-reflex amplitude was shown to be neither indicative of PAP nor PAPE. This review provides preliminary findings suggesting that certain sEMG parameters could be indicative of PAP/PAPE. However, due to limited studies, future research is warranted.

Background/Objectives: Circadian rhythm (CR) influences various physiological functions, including physical and cognitive performance, which fluctuate throughout the day. The present study aimed to investigate the combined and separate effects of CR and physical fatigue on cognitive and physical performance. Methods: A sample of 18 amateur athletes was subjected to a series of tests at three different times of the day: morning, afternoon, and evening. Fatigue was induced following an isokinetic concentric exercise combined with a 20 min treadmill run, followed by assessments of selected physical and cognitive tasks. Results: A repeated measure ANOVA did not reveal an interaction between CR and fatigue in cognitive performance (p > 0.05). However, a significant main effect of fatigue was observed in visual reaction time (VisRT) across all three timepoints. Moreover, peak torque (PT) and the peak torque fatigue index (PTFI) showed significant differences between the three times of the day, peaking in the evening. Conclusions: Although we found no interaction between CR and the physical fatigue state on selected cognitive parameters at the three times of the day, a separate effect of fatigue on cognitive performance was identified. Additionally, physical parameters exhibited peak values occurring in the evening hours. Future research should further explore underlying mechanisms that potentially influence cognitive performance at different times of the day.

INPLASY202460047 Are surface electromyography parameters indicative of post-activation potentiation/post-activation performance enhancement, in terms of twitch potentiation and voluntary performanc…

Circadian rhythm (CR) influences various physiological functions, including physical and cognitive performance, which fluctuate throughout the day. The present study aimed to investigate the combined and separate effects of CR and physical fatigue on cognitive and physical performance. A sample of 18 amateur athletes was subjected to a series of tests at three different times of the day: morning, afternoon, and evening. Fatigue was induced following isokinetic concentric exercise combined with a 20-minute treadmill run, followed by assessments of selected physical and cognitive tasks. Repeated measures ANOVA did not reveal an interaction between CR and fatigue in cognitive performance (p > 0.05). However, a significant main effect of fatigue was observed in visual reaction time (VisRT) across all three time points. Moreover, peak torque (PT) and peak torque fatigue index (PTFI) showed significant differences between the three times of the day, peaking in the evening. Although we found no interaction between CR and physical fatigue state on selected cognitive parameters at the three times of day, a separate effect of fatigue on cognitive performance was identified. Additionally, physical parameters exhibited peak values occurring in the evening hours. Future research should further explore underlying mechanisms that potentially influence cognitive performance at different times of the day.

Background: Strength-Duration (S-D) assessment is commonly used in clinics to examine the excitability of peripheral nerves and muscles. Yet, how changes in neuromuscular excitability relates to improved athletic and muscular performance in healthy subjects remains poorly understood. Therefore, the aim of the study was to evaluate the electrophysiological changes in neuromuscular excitability in the vastus medialis (VM) muscle, using the S-D assessment, following a back squat conditioning activity (BS-CA) protocol designed to elicit a post-activation potentiation (PAP)/post-activation performance enhancement (PAPE) effect. Methods: Eleven athletic males were included in this study. All subjects performed two trials: one examining their BS one-repetition maximum (1 RM) and a main experiment. During the main experiment, baseline levels of rectangular rheobase (R-RIC), triangular rheobase (R-DIC) and chronaxie was collected from the VM muscle, following a standard warmup. Subsequently, the subjects performed three warmup BS-sets and executed a top set of five repetitions (reps) at 80% of 1RM. Afterwards, R-RIC, R-DIC and chronaxie was reassessed for pre and post analysis. Based on these S-D curve (SDC) parameters, the muscle adjustability quotient (MAQ) and threshold charge (Q) was also computed and compared. Results: The R-RIC, R-DIC and Q were all significantly higher following the BS-CA, compared to pre-intervention (p < 0.001). No significant differences were observed for the chronaxie and MAQ (p > 0.05), although an increasing trend was noted (p = 0.054). Conclusions: Based on the findings from this study, the neuromuscular excitability in the VM muscle can be acutely altered following a BS-CA-protocol. However, these changes seems to be more related to muscle fatigue than PAP/PAPE. Nevertheless, S-D assessment may broaden our understanding of the fatigue process during exercise.

Background: Strength-Duration (S-D) assessment is commonly used in clinics to examine the excitability of peripheral nerves and muscles. Yet, how changes in neuromuscular excitability relate to improved athletic and muscular performance in healthy subjects remains poorly understood. Therefore, the aim of the study was to evaluate the electrophysiological changes in neuromuscular excitability in the vastus medialis (VM) muscle using the S-D assessment, following a back squat conditioning activity (BS-CA) protocol designed to elicit a post-activation potentiation (PAP)/post-activation performance enhancement (PAPE) effect in healthy athletic males. Methods: Eleven male physical education students were included in this study. All subjects performed two trials: one examining their BS one-repetition maximum (1-RM), and a main experiment. During the main experiment, baseline levels of rectangular rheobase (R-RIC), triangular rheobase (R-DIC), and chronaxie were collected from the VM muscle following a standard warmup. Subsequently, the subjects performed four warmup BS sets and executed a top set of five repetitions (reps) at 80% of 1-RM. Afterwards, R-RIC, R-DIC, and chronaxie were reassessed for pre and post analysis. Based on these S-D curve (SDC) parameters, the muscle adjustability quotient (MAQ) and threshold charge (Q) were also computed and compared. Results: The R-RIC, R-DIC and Q were all significantly higher following the BS-CA, compared to pre-intervention (p < 0.001). No significant differences were observed for the chronaxie and MAQ (p > 0.05), although an increasing trend was noted for the chronaxie (p = 0.054). Conclusions: Based on the findings from this study, the neuromuscular excitability in the VM muscle can be acutely altered following a BS-CA protocol. However, these changes seem to be more related to muscle fatigue than PAP/PAPE. Nevertheless, S-D assessment may broaden our understanding of the fatigue process during exercise.