Work volume is an important variable in determining the degree of inhibitory control improvements following resistance exercise

Exploring Temporal and Intensity Effects of Resistance Exercise on Inhibition: A Four-Arm Crossover Randomized Controlled Trial

Objective

Given the recognized benefits of resistance exercise on both physical and cognitive domains, elucidating how to maximize its benefit is pivotal. This study aims to evaluate these effects in terms of their timing and intensity on cognitive performance.

Methods

This was a four-arm, crossover randomized controlled trial. Healthy college-aged male adults with recreational resistance training experience participated in this study. Participants completed three separate sessions of circuit barbell resistance exercises, including back squat, press, and deadlift. Each session corresponded to a different intensity level: 65% 1RM, 72% 1RM, and 78% 1RM. Each session consisted of 5 repetitions across 3 sets, with a 3-minute rest between exercises and sets. For the control condition, participants engaged in a reading activity for the same duration. The subjective exercise intensity was measured using the rating of perceived exertion and repetitions in reserve immediately after each set. The primary outcome was the temporal effect of acute resistance exercise on inhibition, measured by the Stroop color-word task. The secondary outcome was the effect of different intensities.

Results

30 out of 31 recruited participants were randomized, with 28 completing all experiment sessions. Using repeated measures correlation (rrm), a linear temporal effect was observed on accuracy-adjusted congruent reaction time: rrm = 0.114, p = 0.045, 95% CI [0.002, 0.223]. Participants responded 19.1 ms faster than the control condition approximately 10 minutes post-intervention. This advantage, however, gradually declined at a rate of 4.3 ms every 15 minutes between 10-55 minutes post-intervention. In contrast, no significant effects were detected for incongruent trials or the Stroop effect. When examining the linear relationship across exercise intensities, no significant correlations emerged for congruent trials.

Conclusion

Resistance exercise demonstrates a temporal effect on cognitive performance, particularly in reaction speed for congruent trials, without significant changes in incongruent trials or the overall Stroop effect. The findings highlight the importance of timing in leveraging the cognitive benefits of acute resistance exercise, suggesting a window of enhanced cognitive performance following exercise. However, this study has a limitation regarding Type I error inflation, due to multiple measurements of cognitive performance being undertaken, suggesting caution in interpreting the observed temporal effects. Practically, scheduling crucial, cognitively demanding tasks within 10-60 minutes post-exercise may maximize benefits, as positive effects diminish after this period.

Effects of resistance exercises on inhibitory control and plasma epinephrine levels: A registered report of a crossover randomized controlled trial

According to the locus coeruleus-norepinephrine (LC-NE) theory, activity of the LC, the major releaser of NE in the brain, regulates inhibitory control. As there is reciprocal communication between circulating epinephrine and the LC, plasma epinephrine is used as the index of LC-NE activity. The aim of this crossover randomized controlled trial is to expand on previous findings by investigating the effects of free-weight, multiple-joint, and structural barbell resistance exercises. Previous studies have had some methodological limitations, such as failure to report the process of randomization, absence of resistance exercise familiarization before the maximal strength testing, and lack of protocol publication. To address these issues, this study incorporates resistance exercise familiarization, transparent reporting of randomization, and submission as a registered report. The results suggest that a single session of resistance exercise (barbell squat, press, and deadlift) with an intensity of 65%-78% 1RM for five repetitions (70%-90% relative intensity) and three sets with 3-min rest intervals improved Stroop congruent reaction time (RT) only (t(27) = -2.663, mean reduction = -15 ms, p = .013, 95% CI [-26, -3]). No significant enhancements were observed in Stroop incongruent RT, inhibitory control as indexed by Stroop effect, or inhibitory control as indexed by the RT difference between the Stroop task and the simple reaction task. Moreover, the alterations in plasma epinephrine levels did not significantly associate with changes in any measure of cognitive performance.

Effects of Acute Resistance Exercise on Executive Function: A Systematic Review of the Moderating Role of Intensity and Executive Function Domain

BACKGROUND

Research has demonstrated that there is a beneficial effect of acute exercise on cognitive function; however, the moderators of the acute resistance exercise (RE) effect on executive function (EF) are underestimated. This systematic review aims to clarify the effects of acute RE on EF by examining the moderating effect of exercise intensity (light, moderate, and vigorous) and EF domains (inhibitory control, working memory, and cognitive flexibility), as well as their interactions.

METHODS

The search strategy was conducted in four databases (PubMed, Scopus, PsycARTICLES, and Cochrane Library) prior to January 29, 2022. Included studies had to: (1) investigate acute RE in adults with normal cognition and without diagnosed disease; (2) include a control group or control session for comparison; (3) include outcomes related to the core EF domains; and (4) be published in English. The methodological quality of the included studies was judged according to the PEDro scale guidelines.

RESULTS

Nineteen studies were included which included a total of 692 participants. More than half of the outcomes (24/42, 57.14%) indicate that acute RE had a statistically significant positive effect on overall EF. In terms of RE intensity and EF domain, moderate intensity acute RE benefited EF more consistently than light and vigorous intensity acute RE. Acute RE-induced EF benefits were more often found for inhibitory control than for working memory and cognitive flexibility. When considering moderators simultaneously, measuring inhibitory control after light or moderate intensity RE and measuring working memory or cognitive flexibility after moderate intensity RE most often resulted in statistically significant positive outcomes.

CONCLUSION

Acute RE has a beneficial effect on EF, observed most consistently for inhibitory control following moderate intensity RE. Future studies should include all exercise intensities and EF domains as well as investigate other potential moderators to enable a better understanding of the benefits of acute RE on EF.

The Effects of Tai Chi on the Executive Functions and Physical Fitness in Middle-Aged Adults with Depression: A Randomized Controlled Trial

Objective

The present study examined the effects of Tai Chi exercise on the executive functions (EFs) and physical fitness of middle-aged adults with depression.

Methods

A total of 39 middle-aged adults with depression (M_age = 50.59, SD = 7.38) were randomly assigned to the Tai Chi group (n = 20) or the waiting-list control group (n = 19). The Tai Chi group engaged in two 90 min sessions of Tai Chi exercise per week for 12 weeks; the waiting-list control group was asked to maintain their usual daily routines for 12 weeks. Depression symptoms, EFs (i.e., inhibitory control, planning, working memory, and cognitive flexibility), and physical fitness (i.e., cardiovascular fitness, muscular strength, muscular endurance, power, and flexibility) were evaluated at the baseline (pretest), 6-week (mid-test), and 12-week (post-test) marks.

Results

Both groups showed decreased depression symptoms over time. Compared with the control group, the Tai Chi group showed decreased reaction times for incongruent conditions in the Stroop test from pretest to mid- and post-test, and shorter reaction time for incongruent conditions in the Stroop test than the control group at post-test; the Tai Chi group performed significantly better than the control group in overall total move score of Tower of London (TOL). The Tai Chi group also showed increased total correct scores of TOL from pretest to mid- and post-test, and greater total correct scores of TOL than the control group at post-test. Additionally, results indicated that Tai Chi exercise comprehensively improved physical fitness from pretest to mid- and post-test. Greater performance in terms of cardiovascular fitness, muscular strength, and power was also found in the Tai Chi group at post-test than in the control group.

Conclusions

These findings suggest that the 12-week Tai Chi exercise improved inhibitory control, planning and working memory aspects of executive functions, and physical fitness in middle-aged adults with depression.

Impact of Inter-Set Short Rest Interval Length on Inhibitory Control Improvements Following Low-Intensity Resistance Exercise in Healthy Young Males

The length of rest interval between sets (i.e., inter-set rest interval) is an important variable for resistance exercise program. However, the impact of the inter-set rest interval on improvements in cognitive function following resistance exercise remains unknown. In this study, we compared the effect of short rest interval (SRI) vs. long rest interval (LRI) protocols on post-exercise cognitive inhibitory control (IC) improvements induced by low-intensity resistance exercise. Twenty healthy, young males completed both SRI and LRI sessions in a crossover design. The bilateral knee extensor low-intensity resistance exercise was programed for six sets with 10 repetitions per set using 40% of one-repetition maximum. The inter-set rest interval lengths for SRI and LRI protocols were set for 1 and 3min, respectively. The color-word Stroop task (CWST) was administrated at six time points: baseline, pre-exercise, immediate post-exercise, and every 10min during the 30-min post-exercise recovery period. The levels of blood lactate, which may be an important determinant for improving IC, throughout the 30-min post-exercise recovery period were significantly higher following SRI protocol than following LRI protocol (p=0.002 for interaction effect). In line with this result, large-sized decreases in the reverse-Stroop interference score, which represent improved IC, were observed immediately after SRI protocol (d=0.94 and 0.82, respectively, vs. baseline and pre-exercise) as opposed to the moderate-sized decreases immediately after LRI protocol (d=0.62 and 0.66, respectively, vs. baseline and pre-exercise). Moreover, significant decreases in the reverse-Stroop interference score were observed from 10 to 30min after SRI protocol (all ps<0.05 vs. baseline and/or pre-exercise), whereas no such decrease was observed after LRI protocol. Furthermore, the degree of decreases in the reverse-Stroop interference score throughout the 30-min post-exercise recovery period was significantly greater in SRI protocol than in LRI protocol (p=0.046 for interaction effect). We suggest that the SRI protocol is more useful in improving post-exercise IC, potentially via greater circulating lactate levels, compared to the LRI protocol. Therefore, the inter-set rest interval length may be an important variable for determining the degree of cognitive function improvements following resistance exercise in healthy young males.

Similar improvements in cognitive inhibitory control following low-intensity resistance exercise with slow movement and tonic force generation and high-intensity resistance exercise in healthy young adults: a preliminary study

This study compared the effects of low-intensity resistance exercise with slow movement and tonic force generation (ST-LRE) and high-intensity resistance exercise (HRE) on post-exercise improvements in cognitive inhibitory control (IC). Sixteen young males completed ST-LRE and HRE sessions in a crossover design. Bilateral knee extensor ST-LRE and HRE (8 repetitions/set, 6 sets) were performed with 50% of one-repetition maximum with slow contractile speed and 80% of one-repetition maximum with normal contractile speed, respectively. The IC was assessed using the color-word Stroop task at six time points: baseline, pre-exercise, immediate post-exercise, and every 10 min during the 30-min post-exercise recovery period. The blood lactate response throughout the experimental session did not differ between ST-LRE and HRE (condition × time interaction P = 0.396: e.g., mean ± standard error of the mean; 8.1 ± 0.5 vs. 8.1 ± 0.5 mM, respectively, immediately after exercise, P = 0.983, d = 0.00). Large-sized decreases in the reverse-Stroop interference scores, which represent improved IC, compared to those before exercise (i.e., baseline and pre-exercise) were observed throughout the 30 min post-exercise recovery period for both ST-LRE and HRE (decreasing rate ≥ 38.8 and 41.4%, respectively, all ds ≥ 0.95). The degree of post-exercise IC improvements was similar between the two protocols (condition × time interaction P = 0.998). These findings suggest that despite the application of a lower exercise load, ST-LRE improves post-exercise IC similarly to HRE, which may be due to the equivalent blood lactate response between the two protocols, in healthy young adults.

Effect of intermittent isometric handgrip exercise protocol with short exercise duration on cognitive performance

The handgrip exercise, a small muscle exercise, is useful for exercise therapy, particularly in the elderly and bedridden patients. The isometric handgrip (IHG) exercise has been utilized in training programs to reduce resting blood pressure; however, the acute effects of the IHG exercise on cognitive performance are not fully understood. The present study aimed to investigate the effect of an intermittent IHG exercise protocol with short exercise duration, which minimizes the arterial blood pressure response to exercise, on cognitive performance. Twenty-two young healthy subjects performed the intermittent IHG exercise protocol, which consisted of 30-s IHG and 45-s recovery × 16 trials; the exercise intensity of the IHG exercise was 30% of the maximal voluntary contraction. Cognitive performance was evaluated before and after the exercise with the Go/No-Go and memory recognition tasks. Specifically, the reaction time (RT) and performance accuracy were measured. The intermittent IHG exercise protocol did not change the RT or performance accuracy of either the Go/No-Go task (P = 0.222 and P = 0.260, respectively) or the memory recognition task (P = 0.427 and P = 0.245, respectively). These findings suggest that the intermittent IHG exercise protocol with short exercise duration may not provide enough stimulation to improve cognitive performance despite being useful as a safe exercise therapy in the elderly and in patients with cardiovascular disease.

Effect of very low-intensity resistance exercise with slow movement and tonic force generation on post-exercise inhibitory control

Background

The extremely low loads (e.g., <30% of one-repetition maximum) involved in performing resistance exercise are effective in preventing musculoskeletal injury and enhancing exercise adherence in various populations, especially older individuals and patients with chronic diseases. Nevertheless, long-term intervention using this type of protocol is known to have little effects on muscle size and strength adaptations. Despite this knowledge, very low-intensity resistance exercise (VLRE) with slow movement and tonic force generation (ST) significantly increases muscle size and strength. To further explore efficacy of ST-VLRE in the clinical setting, this study examined the effect of ST-VLRE on post-exercise inhibitory control (IC).

Methods

Twenty healthy, young males (age: 21 ± 0 years, body height: 173.4 ± 1.2 cm, body weight: 67.4 ± 2.2 kg) performed both ST-VLRE and normal VLRE in a crossover design. The load for both protocols was set at 30% of one-repetition maximum. Both protocols were programmed with bilateral knee extension for six sets with ten repetitions per set. The ST-VLRE and VLRE were performed with slow (3-sec concentric, 3-sec eccentric, and 1-sec isometric actions with no rest between each repetition) and normal contractile speeds (1-sec concentric and 1-sec eccentric actions and 1-sec rests between each repetition), respectively. IC was assessed using the color-word Stroop task at six time points: baseline, pre-exercise, immediate post-exercise, and every 10 min during the 30-min post-exercise recovery period.

Results

The reverse-Stroop interference score, a parameter of IC, significantly decreased immediately after both ST-VLRE and VLRE compared to that before each exercise (decreasing rate >32 and 25%, respectively, vs. baseline and/or pre-exercise for both protocols; all Ps < 0.05). The improved IC following ST-VLRE, but not following VLRE, remained significant until the 20-min post-exercise recovery period (decreasing rate >48% vs. baseline and pre-exercise; both Ps < 0.001). The degree of post-exercise IC improvements was significantly higher for ST-VLRE than for VLRE (P = 0.010 for condition × time interaction effect).

Conclusions

These findings suggest that ST-VLRE can improve post-exercise IC effectively. Therefore, ST-VLRE may be an effective resistance exercise protocol for improving cognitive function.