The Evolution of the Physical Work Capacity at the Fatigue Threshold Test: Past, Present, and Future

Caffeine Expectancy Does Not Influence the Physical Working Capacity at the Fatigue Threshold

ABSTRACT

Ambrozy, CA, Hawes, NE, Hayden, OL, Sortzi, I, and Malek, MH. Caffeine expectancy does not influence the physical working capacity at the fatigue threshold. J Strength Cond Res 38(6): 1056-1062, 2024-The placebo effect occurs when a desired outcome is experienced due to the belief that a treatment is effective, even in the absence of an active ingredient. One explanation for this effect is based on a person's expectations of a drug or supplement. Although caffeine's effects on sports performance have been studied, little is known about how expectations of caffeine affect neuromuscular fatigue during continuous muscle action. The physical working capacity at the fatigue threshold (PWCFT) can be used to assess neuromuscular fatigue noninvasively using surface electromyography. Thus, the purpose of this study was to investigate whether caffeine expectancy influences PWCFT. We hypothesized that regardless of expectancy, caffeine consumption would delay neuromuscular fatigue. The study involved 8 healthy college-aged men (mean ± SEM: age, 25.6 ± 1.0 years) who visited the laboratory on 4 occasions, each separated by 7 days. The subjects completed 4 experimental conditions, in random order, where they were told that they were consuming caffeine or placebo and either received caffeine or placebo. After consuming the drink, the subjects remained in the laboratory for an hour and then performed an incremental exercise test. The results showed that the condition where subjects were told that they were consuming caffeine and received caffeine had significantly higher mean values for maximal power output (F(3, 21) = 11.75; p < 0.001), PWCFT (F(3, 21) = 12.28; p < 0.001), PWCFT (%maximal power output; F(3, 21) = 8.75; p < 0.001), and heart rate at end exercise (%predicted; F(3, 21) = 3.83; p = 0.025) compared with the 2 conditions where placebo was received. However, no statistically significant mean differences were found from the condition where subjects were told that they were consuming placebo but consuming caffeine. This suggests that a person's expectancy and potential somatic response may serve as a cue for how an ergogenic aid or placebo could affect subsequent performance.

The Influence of Cold Therapy on the Physical Working Capacity at the Electromyographic Threshold for Consecutive Exercise Sessions

BACKGROUND

The purpose of this study was to determine whether cold therapy after the first exercise test influences the physical working capacity at the fatigue threshold (PWCFT) during the second exercise test. We hypothesized that cold therapy would delay the onset of PWCFT for the second exercise test relative to the control visit (i.e., no cold therapy).

METHODS

Eight healthy college-aged men volunteered for the present study. For each of the two visits, subjects performed incremental, single-leg, knee-extensor ergometer, followed by either resting for 30 min (control visit) or having a cold pack applied for 15 min and then resting for 15 min (experimental visit). Then, the same exercise test was performed. The order of visits (control vs. experimental) was randomized for each subject. The exercise indices and PWCFT were determined for each of the two visits and statistically analyzed using two-way repeated measures analysis of variance.

RESULTS

The results indicate no significant (p > 0.05) mean differences for maximal power output, heart rate at end-exercise, and PWCFT between the control and cold therapy visits. Moreover, there were no significant (p > 0.05) mean differences between the first and second exercise workbout within each visit.

CONCLUSIONS

The findings of this study suggest that cold therapy did not influence neuromuscular fatigue.

Listening to Music Pretask on Neuromuscular Fatigue During Exercise: Preferred vs. Nonpreferred Music

ABSTRACT

Diehl, TL, Yu, JN, Storer, FM, and Malek, MH. Listening to music pretask on neuromuscular fatigue during exercise: preferred vs. nonpreferred music. J Strength Cond Res 37(7): 1537-1542, 2023-Studies indicate that listening to music can elicit various physiological responses ranging from distracting the subject from the sensation of fatigue to changes in specific regions of the brain. Indeed, the use of music, as an ergogenic aid, to improve human performance has been shown to be a powerful tool. Many studies on the effect of music on human performance have had subjects listen to music in-task (i.e., during the activity). There is, however, a growing interest to determine the role of listening to music pretask (i.e., before the activity) on exercise outcomes. In addition, it is important to consider the subject's music preference as that may influence the target outcome variable(s). Therefore, the purpose of this study was to determine whether listening to preferred music pretask influences the physical working capacity at the fatigue threshold (PWC FT ). We hypothesized that listening to preferred music pretask will increase the estimated PWC FT compared with the control condition, which is listening to nonpreferred music. Nine healthy college-aged men (mean ± SEM : age, 23.4 ± 0.4 years; body mass, 71.6 ± 2.5 kg; and height, 1.81 ± 0.02 m) volunteered for this study. Each subject visited the laboratory on 2 occasions separated by 7 days. In a randomized manner, subjects listened to their preferred music for 30 minutes before the exercise test for 1 visit, whereas for the other visit, subjects listened to their nonpreferred music 30 minutes before the exercise test. Exercise outcomes were recorded for both visits and analyzed using a paired-samples t test. The results indicated no significant ( p > 0.05) mean differences for maximal power output (mean ± SEM : 60 ± 4 W vs. 60 ± 4 W), PWC FT (25 ± 3 W vs. 29 ± 2 W), or heart rate at end exercise (153 ± 8 b·min -1 vs. 155 ± 7 b·min -1 ) between listening to nonpreferred vs. preferred music 30 minutes before the exercise activity. These findings suggest that listening to music pretask does not influence neuromuscular fatigue during the exercise workbout.