An electromyographic analysis of combining weights and elastic tubes as a method of resistance for exercise

The study aimed to compare the effects of elastic and weight resistance exercise on muscular activation patterns. Twenty‐one moderately active males (age = 25 ± 8) performed ten bicep curls and leg extensions with weights (W), an equivalent elastic resistance (T), and a combined condition (TW) of half elastic tension and half weight resistance. Muscular activations of the biceps, triceps, rectus femoris, vastus medialis, and lateralis were recorded with Trigno wireless electrodes, and joint angles were recorded with Qualisys Track Manager. Biceps total activation was highest (P < .001) with weights during the bicep curl due to an increased (P ≤ .007) activation in the eccentric phase. The biceps was also active over a larger portion of the ROM under TW (110°‐70° elbow angle), while W and T exhibited peak activations at mid (90°)‐ and late (50°) stages of ROM, respectively. The triceps (bicep curl) was least active (P < .05) with W throughout the concentric phase, as were the vastus medialis and lateralis (leg extension). Although peak and total activation were similar for most muscles in all conditions, muscular activation patterns differed between conditions indicating that TW may enhance strength gains by increasing time under tension, engaging agonist muscles at less advantageous lengths, and increasing the recruitment of auxiliary muscles

Acute and long-term sleep measurements produce opposing results on sleep quality in 8 and 12 hour shift patterns in law enforcement officers

The occupational demands of law enforcement increase the risk of poor-quality sleep, putting officers at risk of adverse physical and mental health. This cross-sectional study aimed to characterise sleep quality in day workers, 8 and 12 h rotating shift pattern workers. One hundred eighty-six officers volunteered for the study (37 female, age: 41 ± 7). Sleep quality was assessed using the Pittsburgh sleep quality index, actigraphy and the Leeds sleep evaluation questionnaire. The maximal aerobic capacity (VO2max) was measured on a treadmill via breath-by-breath analysis. There was a 70% overall prevalence of poor sleepers based on Pittsburgh sleep quality index scores, where 8 h shifts exhibited the worst prevalence (92%, p = 0.029), however, there was no difference between age, gender, or role. In contrast, 12 h shifts exhibited the poorest short-term measures, including awakening from sleep (p = 0.039) and behaviour following wakefulness (p = 0.033) from subjective measures, and poorer total sleep time (p = 0.024) and sleep efficiency (p = 0.024) from the actigraphy. High VO2max predicted poorer wake after sleep onset (Rsq = 0.07, p = 0.05) and poorer sleep latency (p = 0.028). There was no relationship between the Pittsburgh sleep quality index scores and any of the short-term measures. The prevalence of poor sleepers in this cohort was substantially higher than in the general population, regardless of shift pattern. The results obtained from the long- and short-term measures of sleep quality yielded opposing results, where long-term perceptions favoured the 12 h pattern, but short-term subjective and objective measures both favoured the 8 h pattern

Bilateral Improvements Following Unilateral Home-Based Training in Plantar Flexors: A Potential for Cross-Education in Rehabilitation

CONTEXT: Cross-education (CE) refers to neuromuscular gains in the untrained limb upon contralateral limb training. To date, only laboratory-based exercise programs have demonstrated CE. Home-based exercise prescription eliciting CE could have greater clinical applicability. OBJECTIVE: To determine the effect of an 8-week, home-based unilateral strength training intervention on isokinetic muscle strength, muscular excitation, and power in trained and untrained plantar flexors. DESIGN: Randomized controlled trial. METHODS: Thirty-four healthy participants were randomized to intervention (n = 20) or control (n = 14). The intervention group completed 3 sets of 12 repetitions of progressively loaded unilateral calf raises 3 days per week. Concentric and eccentric peak torque were measured using isokinetic dynamometry at 30°/s and 120°/s. Maximal electromyogram amplitude was simultaneously measured. Power was measured using a jump mat. All variables were measured at preintervention, midintervention, and postintervention. RESULTS: Strength significantly increased bilaterally pre-post at both velocities concentrically and eccentrically in intervention group participants. Maximal electromyogram amplitude significantly increased pre-post bilaterally at both velocities in the medial gastrocnemii of the intervention group. Power significantly increased bilaterally pre-post in the intervention group, with a dose-response effect demonstrated in the untrained plantar flexors. The CE effects of strength, power, and electromyogram activation were 23.4%, 14.6%, and 25.3%, respectively. All control group values were unchanged pre-post. CONCLUSION: This study shows that a simple at-home unilateral plantar flexor exercise protocol induces significant increases in contralateral strength, muscular excitation, and power. These results suggest the applicability of CE in home rehabilitation programs aiming to restore or maintain neuromuscular function in inactive individuals or immobilized ankles

Decreased Exercise-Induced Changes in Prefrontal Cortex Hemodynamics Are Associated With Depressive Symptoms

People with a depressed mood tend to perform poorly on executive function tasks, which require much of the prefrontal cortex (PFC), an area of the brain which has also been shown to be hypo-active in this population. Recent research has suggested that these aspects of cognition might be improved through physical activity and cognitive training. However, whether the acute effects of exercise on PFC activation during executive function tasks vary with depressive symptoms remains unclear. To investigate these effects, 106 participants were given a cardiopulmonary exercise test (CPET) and were administered a set of executive function tests directly before and after the CPET assessment. The composite effects of exercise on the PFC (all experimental blocks) showed bilateral activation changes in dorsolateral (BA46/9) and ventrolateral (BA44/45) PFC, with the greatest changes occurring in rostral PFC (BA10). The effects observed in right ventrolateral PFC varied depending on level of depressive symptoms (13% variance explained); the changes in activation were less for higher levels. There was also a positive relationship between CPET scores (VO2peak) and right rostral PFC, in that greater activation changes in right BA10 were predictive of higher levels of aerobic fitness (9% variance explained). Since acute exercise ipsilaterally affected this PFC subregion and the inferior frontal gyrus during executive function tasks, this suggests physical activity might benefit the executive functions these subregions support. And because physical fitness and depressive symptoms explained some degree of cerebral upregulation to these subregions, physical activity might more specifically facilitate the engagement of executive functions that are typically associated with hypoactivation in depressed populations. Future research might investigate this possibility in clinical populations, particularly the neural effects of physical activity used in combination with mental health interventions

A comparative analysis of muscle activation profiles of elastic and weight resistance exercise

The use of elastic materials in implemented as a resistance method for exercise in both rehabilitation and performance contexts. Despite the increasing popularity of this material, there is paucity of research on muscular responses that occur as a result of using it as a resistance method for exercise. The specific muscular activation patterns that occur throughout the range of motion (ROM) of an exercise can have a crucial impact on strength adaptations and their identification is imperative to the applicability of elastic training in different exercise settings. This project, therefore, aimed to provide an understanding of muscular responses elicited by elastic resistance during exercise. The project consisted of five studies, of which four analytical and one intervention. The first study compared the patterns in muscular activation produced in response to exercising with elastic and weight resistance. Electromyographic responses of the agonist, antagonist and synergist muscles portrayed opposing muscular activation patterns with either method and higher activation of auxiliary muscles with elastic resistance. It was proposed that, due to the opposing activation patterns, the two methods may result in differing architectural adaptations of the skeletal muscles involved, indicating that they could be effectively used as complementary resistance methods. The higher engagement of auxiliary muscles further indicates that elastic resistance may be more effective at improving proprioception and joint stability than weight resistance. The second study analysed the effect of movement velocity on muscular activation patterns with elastic and weight resistance. Peak muscular activation increased at higher velocities with both methods. However, the previously observed activation patterns (Study 1) became more pronounced at higher velocities, where peak activation occurred at earlier stages of movement with weight resistance, but remained at final stages of movement with elastic resistance. These results further indicate that architectural adaptations of the muscles involved may differ substantially with the long term implementation of either method, and that the combined use of elastic and weight resistance may prove beneficial in high speed resistance training in order to maximise muscle overload throughout the ROM. The third study analysed the effects of combining half elastic and half weight resistance on muscular activation patterns. The combined condition portrayed a plateau in muscular activation for most of the concentric phase, as opposed to the peaks exhibited by the two methods on their own, and both the elastic and combined condition exhibited a greater engagement of secondary muscles than weight resistance, indicating that combining the two resistances does effectively maximise muscle overload throughout the concentric phase, offering the added benefit of engaging auxiliary muscles more than weight resistance alone. The fourth study analysed the effect of multiple repetitions with either resistance method on electromyographic indicators of fatigue. Results indicated that elastic and weight resistances induce fatigue of the agonist muscle at similar rates, while synergist and antagonist muscles may fatigue at higher rates under elastic resistance. The final study examined isokinetic and isometric strength adaptations at specific joint angles in response to eight weeks of bicep curl training with elastic resistance, weight resistance or a combination of the two. The opposing patterns in muscular activation elicited by the two methods, observed through the analytical studies, were reflected in angle-specific strength adaptations in the intervention study, where elastic training demonstrated a tendency to produce greater strength gains at stretched muscle lengths and the combination of the two resistances offered mixed responses. The findings indicate an effect of muscular activation pattern on angle specific strength adaptations, emphasizing the importance of understanding the specificity of muscular adaptations for the effective implementation of different resistance methods. In conclusion, elastic and weight resistance produce opposing muscular activation patterns that are enhanced at high movement velocities and effectively complement each other when combined. The activation patterns were reflected in angle-specific strength adaptations through training, suggesting that they may produce different effects on changes in muscle architecture. Finally, auxiliary muscles were more active with elastic resistance, regardless of movement velocity or whether it was combined with weight resistance, indicating that the implementation of elastic resistance is more effective in improving proprioception and joint stability

Comment on Hack et al. Effect of Guarana (<i>Paullinia cupana</i>) on Cognitive Performance: A Systematic Review and Meta-Analysis. <i>Nutrients</i> 2023, <i>15</i>, 434

We have read the recent systematic review and meta-analysis by Hack et al. [...

Cognitive Effects of Guarana Supplementation with Maximal Intensity Cycling

The aim of this study was to investigate the effects of guarana supplementation on cognitive performance before and after a bout of maximal intensity cycling, and to compare this to an equivalent caffeine dose. Twenty-five participants completed the randomised double-blind crossover trial by performing cognitive tests with 1 of 3 supplements, on 3 different days: guarana (125 mg/kg), caffeine (5 mg/kg) or placebo (65 mg/kg protein powder). After 30-minutes of rest, participants performed simple (SRT) and choice reaction time (CRT) tests, an immediate word recall test and Bond-Lader mood scale. This was followed by a cycling V̇O2max test, cognitive tests were then immediately repeated. Guarana supplementation decreased CRT before exercise (407 ± 45ms) in comparison to placebo (421 ± 46ms, P=.030) but not caffeine (417 ± 42ms). SRT after exercise decreased following guarana supplementation (306 ± 28ms) in comparison to placebo (323 ± 32ms, P=.003) but not caffeine (315 ± 32ms). Intraindividual variability on CRT significantly improved from before (111.4 ± 60.5ms) to after exercise (81.85 ± 43.1ms) following guarana supplementation, no differences were observed for caffeine and placebo (P>.05). Alertness scores significantly improved following guarana supplementation (63.3 ± 13.8) in comparison to placebo (57.4 ± 13.4, P=.014) but not caffeine (61.2 ± 12.8). There were no changes to V̇O2max, immediate word recall or any other Bond-Lader mood scales. Guarana supplementation appears to impact several parameters of cognition. These results support the use of guarana supplementation to possibly maintain speed of attention immediately following a maximal intensity exercise test (V̇O2max)

Musculoskeletal Complaints in English Law Enforcement Officers: a cross-sectional study

PURPOSE: Musculoskeletal (MSK) complaints are prevalent in law enforcement officers (LEOs), however research that examines their risk factors is limited. This study aimed to identify the self-reported MSK complaint prevalence and perceived causes in LEOs. METHODS: The Nordic Musculoskeletal Questionnaire was used to identify the 12-month and 7-day prevalence of MSK 'trouble' (ache, pain, discomfort) for 9 body sites. The perceived cause, participant characteristics and occupational role were reported. Body fat percentage was measured using bioelectrical impedance. RESULTS: Complete submissions of 186 questionnaires were received (80% male, median age: 40.6 years, Interquartile Range 10.1). 86% of officers reported having an MSK complaint in the last 12 months, where lower back, shoulder and neck complaint prevalence were 59.1%, 48.4% and 42.5% respectively. Occupational role was associated with the site and presence of complaints (p < 0.05), where armed officers presented with more shoulder, lower back, and hip/thigh complaints. Age, sex and body fat did not impact complaint prevalence. Participants mainly attributed their complaints to occupation equipment or to sport and exercise. CONCLUSION: MSK complaints were highly prevalent in this cohort, particularly armed officers. Further research is required to establish the impact of these complaints and how they can be mitigated