Suchergebnisse

The purpose of this study was to investigate the effects of two different training programs on strength and power performance and serum hormone concentrations. A total of 104 male soldiers volunteered and took part in the 12‐week training period with baseline, mid‐, and post‐measurements of body composition, muscle strength, lower and upper body power, and blood samples to determine serum hormone concentrations. The mean (±SD) age of subjects was 20 ± 1 years, height 180 ± 6 cm and body mass 72.4 ± 8.8 kg. The subjects were divided into three different training groups: soldier task‐specific training (TS), strength training (ST), and control (CON). Each group had a total of 18 training sessions during the 12‐week study. In the muscle strength tests, most improvements could be observed in the TS and ST groups, especially, during the first weeks of the training period. Maximal isometric leg extension force increased significantly by 7.9 ± 12.2% (p < .05) in the TS and 7.1 ± 12.6% (p < .05) in the ST groups between the PRE and MID, as well as between the PRE and POST measurements by 8.1 ± 12.4% (p < .05) in TS and 12.3 ± 15.3% (p < .01) in ST. Serum TES concentration increased significantly in TS between the PRE and MID (16.8 ± 33.9%) and PRE and POST (11.2 ± 16.7%) measurements. Serum COR concentrations decreased in TS between the MID and POST (−7.8 ± 10.9%) and PRE and POST (−11.0 ± 14.3%) measurements. Although the differences observed were rather minor in magnitude, training in the TS and ST groups led to greater improvements in muscle strength and power performance compared to the training in the CON group. The development of strength and/or power of the lower and upper body was greater in the TS and ST groups, which is crucial for warfighter's performance. Therefore, it is important to have a structured resistance‐training program during military training to optimize the strength, power, and military‐specific performance.

A soldier's occupational physical task requirements are diverse and varied. However, the type of physical training that most effectively improves soldiers' occupational task requirements has not been studied previously. The purpose of this study was to determine the important strength characteristics for soldiers during a repeated simulated military task course, and the type of training that may be effective to improve these abilities during a specialized military training period. Forty-two (n = 42) soldiers participated in the study. They were divided into three training groups; a soldier task-specific training group (TSG, n = 17), a strength training group (STG, n = 15), and a control group (CON, n = 10). Participants were measured before (PRE), middle (MID) and after (POST) the 12-week training intervention for strength performance and simulated military task test. Simulated military task performance improved significantly in TSG and STG between the PRE and MID measurements (from 9.4 to 15.7%). TSG and STG improved in various spilt times, especially in strength tasks; casualty drag (from 8.3 to 13.6%) and kettlebell carry (from 13.2 to 22.4%) between the PRE and MID measurements. The present study showed that both the training of TSG and STG were more effective than the training of CON (control group) in terms of improving the performance in the repeated simulated military task course. The present study showed that training of TSG was as effective as STG to improve repeated simulated military task course time. Therefore, an optimal training combination should include high-intensity simulated military task field training and strength training programmed with consideration of the military training phase and environmental possibilities. ; peerReviewed

Introduction: Previous studies have shown that military field training (MFT) has effects on warfighters' hormonal responses, neuromuscular performance, and shooting accuracy. The aim of the present study was to investigate the changes in body composition, upper and lower body strength, serum hormone concentrations of testosterone (TES) and cortisol (COR), insulin-like growth factor-1 (IGF-1), and sex hormone binding globulin (SHBG) and shooting accuracy during prolonged MFT. Methods: Serum hormone concentrations, isometric strength of the upper and lower extremities, and shooting performance were measured four times during the study: before MFT (PRE), after 12 d (MID), at the end of MFT (POST) and after 4 d recovery (RECO). The study was approved by the Finnish Defence Forces and was granted ethical approval by the Ethical Committee of the University of Jyväskylä. Results: There was no change in prone shooting score between the measuring points. In the standing position, however, there was a significant (p ≤ 0.001) decrease from PRE 58.2 ± 12.3 points to MID 45.2 ± 10.4 points. Also POST 61.4 ± 10.8 points and RECO 56.8 ± 13.6 points were significantly (p ≤ 0.001) higher than MID 45.2 ± 10.4 points. Serum hormone concentrations of TES and IGF-1 decreased significantly during MFT. In COR and SHBG concentrations, significant increases were observed during MFT. Individual changes in lower body strength and changes in shooting standing score between the measurement points (PRE–MID/POST/RECO) correlated significantly (r = 0.332, p = 0.031; r = 0.335, p = 0.025; r = 0.489, p = 0.001, respectively). The similar finding was observed with changes in upper body strength and changes in standing shooting between the PRE and RECO measurement points (0.339, p = 0.010). The changes in COR and the changes in prone shooting showed a positive correlation in all measurement points (r = 0.531, p ≤ 0.001; r = 0.337, p = 0.024; r = 0.572, p ≤ 0.001). The changes in IGF-1 correlated negatively (r = −0.325, p = 0.038) with shooting prone between the PRE and MID measurement points. The changes in shooting standing and the changes in TES between PRE and POST correlated negatively (r = −0.378, p = 0.010). Conclusion: In this study, we observed a decrease in leg strength from the PRE to MID measurements. When the physical load requirements during the MFT decreased after the MID measurements, leg strength increased. In addition, the shooting score from the standing position decreased from the PRE to MID measurements and improved significantly from the MID to POST measurements. The prone shooting score did not show any significant changes during the study period. Significant positive correlations were found between the changes in standing shooting score and the changes in strength for the legs and upper body. There was a positive correlation between the changes in serum COR concentrations and changes in standing shooting score. Altogether, the present study showed that the prolonged MFT has adverse effect on the strength levels and the shooting ability in warfighters. This shows that ensuring warfighters get an appropriate amount of rest while performing their duties is important. Shooting from a prone position was not affected by the changing workloads and this result indicated that soldiers should shoot from a prone position, whenever possible, especially when fatigued. ; peerReviewed

Introduction: Few studies have reported the amount of physical activity (PA) and its associations to physical performance of warfighters during military field training (MFT). The purpose of this study was to investigate changes in neuromuscular performance and PA among male Finnish Army conscripts during a 21-d MFT and to evaluate their recovery during 4 d after MFT. Methods: Body composition and physical performance were measured four times during the study (before MFT (PRE), after 12 d (MID), post training (POST) and after 4 d of recovery (RECO)). PA was measured throughout MFT in a group of healthy young male conscripts (n=49) by using a tri-axial accelerometer. The study was approved by the Finnish Defence Forces and was granted ethics approval by the Ethics Committee of the University of Jyväskylä. Results: Body mass declined significantly from 73.5 ± 8.7 to 71.6 ± 8.2 kg, but it recovered close to the PRE values (73.0 ± 8.3 kg). The same trend was also found in skeletal muscle mass and fat mass. The change in body mass and in skeletal muscle mass correlated negatively with the change in vigorous physical activity (r = −0.374, p = 0.016, and r = −0.337, p = 0.031, respectively). Muscular endurance decreased significantly (p < 0.001) in sit-ups from the PRE (46 ± 9 reps/min) values compared with MID (40 ± 8 reps/min), POST (42 ± 8 reps/min), and RECO (34 ± 11 reps/min) values. Also in push-ups, the declines in the POST (34 ± 10 reps/min) and RECO (34 ± 13 reps/min) values (p < 0.001) from the PRE (40 ± 13 reps/min) and MID (39 ± 12 reps/min) values were observed. There was a significant decrease in a standing long jump in all measurement points MID (220 ± 20 cm), POST (216 ± 20 cm), and RECO (213 ± 20 cm) as compared with the PRE values (229 ± 23 cm, p < 0.001). There was no change in 3.2 km loaded march time between the PRE (23:57 ± 4:12 min:s) and POST (23:44 ± 5:02 min:s) measurement time points. In PA, the total number of steps per day was significantly (p < 0.001) greater during ST (13,722 ± 2,379 steps) and MFT (13,937 ± 2,276 steps) than during garrison days (9,550 ± 2,569 steps). In POST, there was significantly (p < 0.001) more light (1.5–3.0 metabolic equivalent) (2:34:38 ± 0:22:53 h:min:s in ST and 3:03:27 ± 0:23:24 h:min:s in MFT) and moderate (3.0–6.0 metabolic equivalent) (2:12:15 ± 0:23:14 h:min:s in ST and 2:47:59 ± 0:27:23 h:min:s in MFT) PA than in the PRE measurements. Conclusion: This study demonstrated slight decrements in warfighter physical performance during the 21-d MFT. The conscripts were overloaded during MFT, but 4 d of recovery seemed not to be enough to obtain the PRE measurement values in physical performance. This study also showed changes in the muscular endurance levels and PA during the 21-d MFT. It is important for warfighters to have a good physical fitness level PRE training or combat. As the prolonged MFT may have adverse effects in warfighters muscular endurance and PA levels, it is important to have sufficient recovery time after long MFT to regain combat readiness. ; peerReviewed

The purpose of this study was to evaluate the associations of physical fitness and body composition characteristics with anaerobic endurance performance, tested in the combat load using the occupationally relevant military simulation test (MST). Eighty-one male soldiers, deployed to a crisis management operation in the Middle East, volunteered for the study and participated in a test battery consisting measurements of muscle strength, body composition characteristics, endurance capacity, and MST. A Spearman correlational analysis revealed that the strongest variable, correlated with MST time, was the countermovement jump performed with the combat load (CMJ2) (rs = 20.66, p , 0.001). Among the individual body composition variables, the MST time had the strongest relationship with fat percentage (rs = 0.53, p , 0.001) and skeletal muscle mass (SMM) (rs = 20.47, p , 0.001). The use of the dead mass ratio, which was calculated dividing body mass by fat mass accompanied with the weight of the combat load, increased body composition-based associations significantly, and this variable turned out to be the best single predictor for the MST performance (rs = 20.67, p , 0.001). Significant predictors of the MST time in the stepwise multivariate regression analysis included CMJ2, 3000 m, SMM, and push-ups. Together, these variables explained 66% (R2 adj ¼ 0:658, model p , 0.001) of the variance in the MST time. In conclusion, the novel MST is a promising military specific assessment method of muscle power of the lower extremities and endurance capacity, which are crucial performance components in anaerobic combat situations. ; peerReviewed

Decreases in aerobic fitness during military operations have been observed in several studies. Thus, differences in training adaptations during a 6-month crisis-management operation were compared by using the change in endurance performance as the outcome measure. Sixty-six male soldiers volunteered for the study, consisting of pre–post assessments of blood biomarkers, body composition, physical performance, and the military simulation test (MST) performance. Physical training volume was self-reported. After the follow-up, the data were divided based on individual changes in endurance performance. Endurance performance was improved in the high-responder group (HiR, n = 25) and maintained or decreased in the low-responder group (LoR n = 24). During the operation, the LoR group decreased while the HiR group increased their endurance training frequency from the pre-deployment level (Δ 28 ± 57% vs. −40 ± 62%, p = 0.004). Fat mass decreased (−7.6 ± 11.7% vs. 14.2 ± 20.4%, p < 0.001), and 1-min push-up (27.7 ± 21.9% vs. 11.7 ± 26.1%, p = 0.004) and MST performance improved (−13.6 ± 6.8% vs. −7.5 ± 6.5%, p = 0.006) more in the HiR group. No differences were observed in the changes of other physical performance test results or analyzed biomarkers. In conclusion, soldiers who were initially leaner and fitter in terms of lower body strength and power were more likely to decrease their aerobic fitness during the operation. ; peerReviewed

Decreases in aerobic fitness during military operations have been observed in several studies. Thus, differences in training adaptations during a 6-month crisis-management operation were compared by using the change in endurance performance as the outcome measure. Sixty-six male soldiers volunteered for the study, consisting of pre–post assessments of blood biomarkers, body composition, physical performance, and the military simulation test (MST) performance. Physical training volume was self-reported. After the follow-up, the data were divided based on individual changes in endurance performance. Endurance performance was improved in the high-responder group (HiR, n = 25) and maintained or decreased in the low-responder group (LoR n = 24). During the operation, the LoR group decreased while the HiR group increased their endurance training frequency from the pre-deployment level (Δ 28 ± 57% vs. −40 ± 62%, p = 0.004). Fat mass decreased (−7.6 ± 11.7% vs. 14.2 ± 20.4%, p < 0.001), and 1-min push-up (27.7 ± 21.9% vs. 11.7 ± 26.1%, p = 0.004) and MST performance improved (−13.6 ± 6.8% vs. −7.5 ± 6.5%, p = 0.006) more in the HiR group. No differences were observed in the changes of other physical performance test results or analyzed biomarkers. In conclusion, soldiers who were initially leaner and fitter in terms of lower body strength and power were more likely to decrease their aerobic fitness during the operation.

Objectives: Generally, operational military duties are associated with a variety of stressors, such as prolonged physical activity (PA). However, limited information is available on the occupational workload or changes in PA during international military operations. Thus, the aim of the study was to investigate the changes in body composition, stress biomarkers, PA, and heart rate (HR) responses of 79 male soldiers during a 6-month international crisis management operation. Material and Methods: Measurements were conducted 3 times in South-Lebanon during the operation. Body composition was assessed by the bioelectrical impedance method. Blood samples were analyzed for serum testosterone, sex-hormone binding globulin (SHBG), cortisol and insulin-like growth factor. Saliva sampling was used for analyzing stress biomarkers, cortisol and α-amylase. Heart rate and physical activity were monitored by a recordable belt and tri-axial accelerometer, respectively. Results: Increases in muscle mass (39.2±4.1 vs. 39.5±4.2 kg, p < 0.05) and testosterone (15.9±4.6 vs. 17.2±4 nmol/l, p < 0.01), and reductions in PA variables (e.g., daily step count 9472±2547 vs. 8321±2720, p < 0.05) were observed during the first half (i.e., PRE-MID) of the study. The increase in muscle mass remained significant during the latter half (PRE-POST, 39.2±4.1 vs. 39.6±4.4 kg, p < 0.05), but also fat mass increased (MID-POST, 10.6±4.6 vs. 11.0±4.7 kg, p < 0.05) while SHBG (MID-POST, 31.8±12.1 vs. 26.6±13.2 nmol/l, p < 0.01) and cortisol (MID-POST, 445±116 vs. 400±123 nmol/l, p < 0.05) decreased. With the exception of increased concentration of salivary α-amylase (PRE-POST, 36.5±33.7 vs. 55.1±39.7 U/ml), the acute stress biomarkers and HR responses remained unchanged. Furthermore, the low quantity of PA, low HR values and subjective ratings of exertion refer to rather light physical workload. Conclusions: Due to the operatively calm nature of the working environment, the present soldiers did not express any significant signs of physical overload during the study period. ; peerReviewed

ABSTRACT: Pihlainen, K, Kyröläinen, H, Santtila, M, Ojanen, T, Raitanen, J, and Häkkinen, K. Effects of combined strength and endurance training on body composition, physical fitness, and serum hormones during a 6-month crisis management operation. J Strength Cond Res XX(X): 000-000, 2020-Very few studies have examined the impact of training interventions on soldier readiness during an international military operation. Therefore, the present study investigated the effects of combined strength and endurance training on body composition, physical performance, and hormonal status during a 6-month international military deployment consisting of typical peacekeeping tasks, e.g., patrolling, observation, and on-base duties. Soldiers (n = 78) were randomly allocated to a control group (C) or one of 3 combined whole-body strength and endurance training groups with varying strength-to-endurance training emphasis (Es = 25/75%, SE = 50/50% or Se = 75/25% of strength/endurance training). Body composition, physical performance (3000-m run, standing long jump [SLJ], isometric maximal voluntary contraction of the lower [MVC lower] and upper extremities [MVC upper ], muscle endurance tests), and selected serum hormone concentrations were determined prior to training (PRE), and after 9 (MID) and 19 (POST) weeks of training. Within- and between-group changes were analyzed using linear regression models. The average combined strength and endurance training frequency of the total subject group was 3 ± 2 training sessions per week. No changes were observed in physical performance variables in the intervention groups, whereas SLJ decreased by 1.9% in C (p < 0.05). Maximal voluntary contraction lower increased by 12.8% in the combined intervention group (p < 0.05), and this was significantly different to C (p < 0.05). Testosterone-to-cortisol ratio increased in SE and Se (p < 0.05), whereas no change was observed in C. The intervention groups maintained or improved their physical performance during deployment, which is beneficial for operational readiness. However, the high interindividual variation observed in training adaptations highlights the importance of training individualization during prolonged military operations. ; publishedVersion ; Peer reviewed

Very few studies have examined the impact of training interventions on soldier readiness during an international military operation. Therefore, the present study investigated the effects of combined strength and endurance training on body composition, physical performance, and hormonal status during a 6-month international military deployment consisting of typical peacekeeping tasks, e.g., patrolling, observation, and on-base duties. Soldiers (n = 78) were randomly allocated to a control group (C) or one of 3 combined whole-body strength and endurance training groups with varying strength-to-endurance training emphasis (Es = 25/75%, SE = 50/50% or Se = 75/25% of strength/endurance training). Body composition, physical performance (3000-m run, standing long jump [SLJ], isometric maximal voluntary contraction of the lower [MVC lower] and upper extremities [MVC upper ], muscle endurance tests), and selected serum hormone concentrations were determined prior to training (PRE), and after 9 (MID) and 19 (POST) weeks of training. Within- and between-group changes were analyzed using linear regression models. The average combined strength and endurance training frequency of the total subject group was 3 ± 2 training sessions per week. No changes were observed in physical performance variables in the intervention groups, whereas SLJ decreased by 1.9% in C (p < 0.05). Maximal voluntary contraction lower increased by 12.8% in the combined intervention group (p < 0.05), and this was significantly different to C (p < 0.05). Testosterone-to-cortisol ratio increased in SE and Se (p < 0.05), whereas no change was observed in C. The intervention groups maintained or improved their physical performance during deployment, which is beneficial for operational readiness. However, the high interindividual variation observed in training adaptations highlights the importance of training individualization during prolonged military operations. ; peerReviewed

We hypothesized that increased oxidative stress and disrupted redox balance may be predisposing factors and markers for overreaching (OR). Purpose: To examine whether oxidative stress markers and antioxidant status and physical fitness are related to overreaching during an 8-week military basic training (BT) period. Methods: Oxidative stress and antioxidant status were evaluated in the beginning, after 4 and 7 weeks of training in 35 males (age 19.7 ± 0.3 yrs) at rest and immediately after a 45-min submaximal exercise. Physical activity (PA) was monitored by accelerometer throughout BT. Indicators of OR were also examined. Results: From baseline to wk4 increased daytime moderate to vigorous PA led to concomitant decreases in the ratio oxidized to total glutathione (GSSG/TGSH) and GSSG. After 4 weeks of BT, GSSG/TGSH and GSSG returned to the baseline values at rest, while PA remained unchanged. At every time point acute exercise decreased TGSH and increased GSSG and GSSG/TGSH, while a decrease was observed in antioxidant capacity after 4 weeks of training. In the beginning of BT, OR subjects (11 of the 35 males) had higher GSSG, GSSG/TGSH and malondialdehyde (a marker of lipid peroxidation) at rest (P<0.01-0.05) and lower response of GSSG and GSSG/TGSH ratio (P<0.01) to exercise than noOR subjects. Moreover, OR subjects had higher PA during BT than noOR (P<0.05). Conclusion: The sustained training load during the last four weeks of BT led to oxidative stress observable both at rest and after submaximal exercise. Increased oxidative stress may be a marker of insufficient recovery leading possibly to OR. ; peerReviewed

Background: Previous military studies have shown an energy deficit during a strenuous field training course (TC). This study aimed to determine the effects of energy bar supplementation on energy balance, physical activity (PA), physical performance and well-being and to evaluate ad libitum fluid intake during wintertime 8-day strenuous TC. Methods: Twenty-six men (age 2061 yr.) were randomly divided into two groups: The control group (n = 12) had traditional field rations and the experimental (Ebar) group (n = 14) field rations plus energy bars of 4.1 MJNday21 . Energy (EI) and water intake was recorded. Fat-free mass and water loss were measured with deuterium dilution and elimination, respectively. The energy expenditure was calculated using the intake/balance method and energy availability as (EI/estimated basal metabolic rate). PA was monitored using an accelerometer. Physical performance was measured and questionnaires of upper respiratory tract infections (URTI), hunger and mood state were recorded before, during and after TC. Results: Ebar had a higher EI and energy availability than the controls. However, decreases in body mass and fat mass were similar in both groups representing an energy deficit. No differences were observed between the groups in PA, water balance, URTI symptoms and changes in physical performance and fat-free mass. Ebar felt less hunger after TC than the controls and they had improved positive mood state during the latter part of TC while controls did not. Water deficit associated to higher PA. Furthermore, URTI symptoms and negative mood state associated negatively with energy availability and PA. Conclusion: An easy-to-use protein-rich energy bars did not prevent energy deficit nor influence PA during an 8-day TC. The high content of protein in the bars might have induced satiation decreasing energy intake from field rations. PA and energy intake seems to be primarily affected by other factors than energy supplementation such as mood state. ; peerReviewed

The present study examined whether activity energy expenditure related to body mass (AEE/kg) is associated with maximal aerobic fitness (VO2max), energy balance, and body mass index (BMI) during the 2 hardest weeks of the military basic training season (BT). An additional purpose was to study the accuracy of the pre-filled food diary energy intake. Energy expenditure (EE) with doubly labeled water, energy intake (EI), energy balance, and mis-recording was measured from 24 male conscripts with varying VO2max. AEE/kg was calculated as (EE × 0.9−measured basal metabolic rate)/body mass. The reported EI was lower (P<0.001) than EE (15.48 MJ/day) and mis-recording of the pre-filled diary was −20%. The negative energy balance (−6±26%) was non-significant; however, the variation was high. The subjects with a low VO2max, a high BMI, and a negative energy balance were vulnerable to low AEE/kg. However, in the multivariate regression analysis only BMI remained in the model, explaining 33% of the variation in AEE/kg. During wintertime BT, AEE/kg is affected by energy balance, VO2max, and BMI. From these three factors, overweight limits high-level training the most. Furthermore, an optimal energy balance facilitates physical performance and enables high training loads to be sustained during the BT season. ; peerReviewed

The purpose was (a) to study the effect of an 8-week Finnish military basic training period (BT) on physical fitness, body composition, mood state, and serum biochemical parameters among new conscripts; (b) to determine the incidence of overreaching (OR); and (c) to evaluate whether initial levels or training responses differ between OR and noOR subjects. Fifty-seven males (19.7 ± 0.3 years) were evaluated before and during BT. Overreaching subjects had to fulfill 3 of 5 criteria: decreased aerobic physical fitness (VO2max), increased rating of perceived exertion (RPE) in 45-minute submaximal test at 70% of VO2max or sick absence from these tests, increased somatic or emotional symptoms of OR, and high incidence of sick absence from daily service. VO2max improved during the first 4 weeks of BT. During the second half of BT, a stagnation of increase in VO2max was observed, basal serum sex hormone-binding globulin (SHBG) increased, and insulin-like growth factor-1 and cortisol decreased. Furthermore, submaximal exercise-induced increases in cortisol, maximum heart rate, and postexercise increase in blood lactate were blunted. Of 57 subjects, 33% were classified as OR. They had higher basal SHBG before and after 4 and 7 weeks of training and higher basal serum cortisol at the end of BT than noOR subjects. In addition, in contrast to noOR, OR subjects exhibited no increase in basal testosterone/cortisol ratio but a decrease in maximal La/RPE ratio during BT. As one-third of the conscripts were overreached, training after BT should involve recovery training to prevent overtraining syndrome from developing. The results confirm that serum SHBG, cortisol, and testosterone/cortisol and maximal La/RPE ratios could be useful tools to indicate whether training is too strenuous. ; peerReviewed

Limited data are available regarding strength and endurance training adaptations to occupational physical performance during deployment. This study assessed acute training-induced changes in neuromuscular (electromyography; EMG) and metabolic (blood lactate, BLa) responses during a high-intensity military simulation test (MST), performed in the beginning (PRE) and at the end (POST) of a six-month crisis-management operation. MST time shortened (145 ± 21 vs. 129 ± 16 s, −10 ± 7%, p < 0.001) during the operation. Normalized muscle activity increased from PRE to POST in the hamstring muscles by 87 ± 146% (116 ± 52 vs. 195 ± 139%EMGMVC, p < 0.001) and in the quadriceps by 54 ± 81% (26 ± 8 vs. 40 ± 20%EMGMVC, p < 0.001). In addition, higher acute BLa values were measured after MST during POST. Changes in BLa and EMG suggested an increased neural input and metabolic rate during POST MST, likely leading to faster performance times at the end of the operation. High EMG values throughout the different phases of MST suggested that despite the anaerobic nature of the test, the soldiers were able to maintain their voluntary muscle activation level until the end of the test. This indicates only limited neural fatigue during the two-minute high-intensity military specific performance. While learning effect may explain some part of the improvement in the MST performance times, combined strength and endurance training three times per week may improve neuromuscular performance in occupationally relevant tasks. ; peerReviewed