Acute effects of commercial energy drink consumption on exercise performance and cardiovascular safety: a randomized, double-blind, placebo-controlled, crossover trial

The aim of this study was to examine the acute effects of a non-caloric energy drink (C4E) compared to a traditional sugar-containing energy drink (MED) and non-caloric placebo (PLA) on exercise performance and cardiovascular safety. Thirty healthy, physically active males (25 ± 4 y) completed three experimental visits under semi-fasted conditions (5-10 h) and in randomized order, during which they consumed C4E, MED, or PLA matched for volume, appearance, taste, and mouthfeel. One hour after drink consumption, participants completed a maximal, graded exercise test (GXT) with measurement of pulmonary gases, an isometric leg extension fatigue test (ISOFTG), and had their cardiac electrical activity (ECG), leg blood flow (LBF), and blood pressure (BP) measured throughout the visit. Neither MED nor C4E had an ergogenic effect on maximal oxygen consumption, time to exhaustion, or peak power during the GXT (p > 0.05). Compared to PLA, MED reduced fat oxidation (respiratory exchange ratio (RER) +0.030 ± 0.01; p = 0.026) during the GXT and did not influence ISOFTG performance. Compared to PLA, C4E did not alter RER (p = 0.94) and improved impulse during the ISOFTG (+0.658 ± 0.25 V·s; p = 0.032). Relative to MED, C4E did not significantly improve gas exchange threshold (p = 0.05-0.07). Both MED and C4E increased systolic BP at rest (+7.1 ± 1.2 mmHg; p < 0.001 and + 5.7 ± 1.0 mmHg; p < 0.001, respectively), C4E increased SBP post-GXT (+13.3 ± 3.8 mmHg; p < 0.001), and MED increased SBP during recovery (+3.2 ± 1.1 mmHg; p < 0.001). Neither MED nor C4E influenced ECG measures (p ≥ 0.08) or LBF (p = 0.37) compared to PLA. C4E may be more efficacious for improving performance in resistance-type tasks without altering fat oxidation under semi-fasted conditions during fatiguing exercise bouts, but promotes similar changes in BP and HR to MED.

A profile of two different applicant test batteries with regards to sex and age in successful law enforcement applicants

BACKGROUND

Law enforcement (LE) applicant assessments and initial academy training vary greatly across the United States of America (USA), with 820+ academies operating across 50 different states. Rising obesity and declining physical fitness underscore the need for benchmarks of applicant physical performance.

OBJECTIVE

Create a "point-in-time" descriptive profile of the performance of LE applicants and determine any differences between males, females, and age using two applicant test batteries (ATBs).

METHODS

Archival data from one large USA LE academy were analysed. Applicants completed one of two ATBs; ATB1 (n = 1674): 68.8-meter agility run (AR), 60-s push-ups, 60-s sit-ups, 60-s arm ergometer revolutions, and 2.4 km run; ATB2 (n = 355): AR, 60-s push-ups, 60-s sit-ups, and a multistage fitness test. Data were coded for sex and age. Independent samples t-tests compared the sexes. A one-way ANOVA with Bonferroni post hoc analysis compared age groups (18- 24, 25- 29, 30- 34, 35- 39, 40 + years).

RESULTS

Males outperformed females in all fitness assessments across both ATBs (p≤0.02). The 18- 24 age group demonstrated faster run times in the AR and 2.4 km for ATB1 compared to all groups. (p≤0.03). In ATB2, the 18- 24 age group was faster in the AR compared to all other groups except the 25- 29 age group (p≤0.026).

CONCLUSIONS

Regardless of ATB used, females and older applicants generally would benefit from specific fitness training to better prepare for academy. Older applicants may experience greater challenges in running tasks, especially those involving sprinting, which could also be impacted by qualities important for running/sprinting (i.e., maximal strength and power).

Characterising the physical demands of critical tasks across the Royal Australian Air Force

BACKGROUND

Militaries have historically utilised generic physical fitness tests to assess physical readiness, but there has been a recent shift to develop physical employment standards (PES) based on actual job demands.

OBJECTIVE

The purpose of this investigation was to characterise the physical demands of critical tasks performed by Royal Australian Air Force (RAAF) personnel to inform PES development.

METHODS

Job task analysis were performed for 27 RAAF trades. Criterion tasks were identified through a systematic approach involving workshops and field-observations. The identified tasks were assessed for dominant physical capacity and grouped into movement-based clusters. Psychophysiological measures were collected from personnel performing the tasks.

RESULTS

Of 87 criterion tasks, 92% were characterised as manual handling dominant. Across these 87 tasks the principal physical capacities were: muscular strength (59%), muscular endurance (52%) and cardiorespiratory endurance (39%). The most common movement clusters were Lift to Platform (44%) and Lift and Carry (38%). Lift to Platform tasks required lifting to a median height of 1.32 m (1.20 -1.65 m) and a median mass of 25.0 kg (21.0 -28.9 kg) per person. Median carry mass was 25.0 kg (22.4 -36.1 kg) per person and distance was 26.0 m (17.5 -50.0 m). Median task mean 'Vdot;O2, HR and RPE were 1.8 L.min- 1 (1.5-2.2 L.min- 1), 137 b.min- 1 (120-144) and 13 (12-14).

CONCLUSIONS

The high proportion of manual handling criterion tasks emphasises the importance of these activities and the underlying physical capacities for RAAF personnel. Current fitness assessments are unlikely to predict job task performance.

Trunk muscle dysfunction in patients with myotonic dystrophy type 2 and its contribution to chronic low back pain

Introduction

Myotonic dystrophy type 2 (MD2) presents with a varied manifestation. Even though the myopathy in these patients is more widespread, axial musculature involvement is one of the most prominent conditions. MD2 patients also often report chronic low back pain (CLBP). The purpose of this study was to evaluate trunk muscle function, including respiratory muscles, in patients with MD2 and to compare it with healthy controls, to determine the occurrence of CLBP in patients with MD2, and to assess whether trunk muscle dysfunction increases the risk of CLBP in these patients.

Methods

We enrolled 40 MD2 patients (age range 23 to 76 years, 26 women). A comprehensive battery of tests was used to evaluate trunk muscle function. The tests consisted of quantitative muscle strength testing of low back extensor muscles and respiratory muscles and the assessment of trunk muscle endurance. A neurological evaluation contained procedures assessing the distribution of muscle weakness, myotonia, and pain, and used questionnaires focused on these items and on disability, depression, and physical activity.

Results

The results of this study suggest that patients with MD2 show significant dysfunction of the trunk muscles, including the respiratory muscles, expressed by decreased muscle strength and endurance. The prevalence of CLBP in patients with MD2 was 52.5%. Based on our analysis, the only independent significant risk factor for CLBP in these patients was maximal isometric lower back extensor strength in a prone position ≤ 15.8 kg (OR = 37.3). Other possible risk factors were severity of myotonia and reduced physical activity.

Conclusion

Outcomes of this study highlighted the presence of axial muscle dysfunction, respiratory muscle weakness, and frequent occurrence of CLBP together with its risk factors in patients with MD2. We believe that the findings of this study may help in management and prevention programs for patients with MD2.

Non-Traditional Physical Education Classes Improve High School Students' Movement Competency and Fitness: A Mixed-Methods Program Evaluation Study

Non-traditional physical education (PE) programs may facilitate functional movement patterns and develop fitness and work capacity to facilitate long-term physical activity. This program evaluation study compared changes in body composition, movement competency, work capacity, and fitness for high school students in CrossFit or weight training PE; both classes were hypothesized to improve each area, with greater improvements in the CrossFit class. Students participated in 57 min classes 4 days per week for 9 months. Measures including body composition, movement competencies (squat, lunge, push-up, pull-up, hinge, and brace), work capacity (two CrossFit workouts), and fitness (air squats, push-ups, inverted row, plank hold, horizontal and vertical jumps, 5 rep max back squat and press, 500 m bike, and 12 min run) were taken at baseline, midpoint, and post-test. Focus groups to assess students' experiences and outcomes were conducted at post-test. Students significantly improved in movement competencies (ps = 0.034 to <0.001), work capacity (ps < 0.001), and all fitness tests (ps = 0.036 to <0.001). The CrossFit class was only superior on the 500 m bike. Four themes were identified from the focus groups: (1) increased self-confidence, (2) health improvements, (3) newfound community, and (4) translational sports improvements. Future research should examine changes using an experimental design.

Effect of Neuromuscular Electrical Stimulation Training on Control of Involuntary Muscular Torque and Stimulation Intensity in Older Adults

The purpose of this study was to examine the effects of a 4-week neuromuscular electrical stimulation (NMES) training regimen on involuntary torque output and electrical stimulation intensity in older adults. Twelve older adults (ages: 68.4 ± 6.5 years; men: n = 6, women: n = 6; weight: 158.6 ± 27.3 lbs; height: 65.2 ± 2.1 in) received submaximal intensity NMES to the quadriceps for 4 weeks to determine training-related changes in stimulation intensity and involuntary control of muscular torque during the NMES protocol. Two-way repeated measures ANOVAs were used to compare torque parameters and stimulation intensity between days and across protocol time bins. After training, stimulation intensity and torque increased over the course of the NMES protocol, while torque decreased during the protocol pre-training. These results suggest that muscular endurance of involuntary muscle contraction is increased with NMES training, and that stimulation intensity should be increased throughout the course of training to augment muscular torque output.

Predicting Total Back Squat Repetitions from Repetition Velocity and Velocity Loss

The purpose of this investigation was to determine if average concentric velocity (ACV) of a single repetition at 70% of one-repetition maximum (1RM), ACV of the first repetition of a set to failure at 70% of 1RM, or the velocity loss during the set could predict the number of repetitions performed in the back squat. Fifty-six resistance-trained individuals participated in the study (male = 41, age = 23 ± 3 yrs, 1RM = 162.0 ± 40.0 kg; female = 15, age = 21 ± 2 yrs, 1RM = 81.5 ± 12.5 kg). After 1RM testing, participants performed single repetition sets with 70% of 1RM and a set to failure with 70% of 1RM. ACV was recorded on all repetitions. Regression model comparisons were performed, and Akaike Information Criteria (AIC) and Standard Error of the Estimate (SEE) were calculated to determine the best model. Neither single repetition ACV at 70% of 1RM (R² = 0.004, p = 0.637) nor velocity loss (R² = 0.011, p = 0.445) were predictive of total repetitions performed in the set to failure. The simple quadratic model using the first repetition of the set to failure (Y=β0+β1XACVFirst+β2Z+ε) was identified as the best and most parsimonious model (R² = 0.259, F = 9.247, p < 0.001) due to the lowest AIC value (311.086). A SEE of 2.21 repetitions was identified with this model. This average error of ~2 repetitions warrants only cautious utilization of this method to predict total repetitions an individual can perform in a set, with additional autoregulatory or individualization strategies being necessary to finalize the training prescription.

Adherence and Effect of Home-Based Rehabilitation with Telemonitoring Support in Patients with Chronic Non-Specific Low Back Pain: A Pilot Study

Home-based exercises have been on the rise recently. This pilot study aimed to assess the adherence and effect of a home-based rehabilitation programme using telemonitoring in patients with chronic non-specific low back pain (CNLBP). Twenty-seven patients with CNLBP were enrolled in the study, each of whom underwent a neurological assessment, including patient-oriented measures and a functional assessment-a battery of tests that comprehensively evaluated trunk muscle function. The rehabilitation programme lasted 18 weeks and included daily home-based exercises. A mobile application or an exercise diary was used to monitor compliance. Adherence to the programme was excellent for both the diary and mobile application groups, with 82.3% in the diary group exercising at least once a day and 72.9% twice a day, and 94.8% in the mobile application group exercising at least once a day and 86.6% twice a day. Both patient-oriented and functional outcomes improved significantly; however, the relative changes of the parameters in these two groups did not correlate, which supports the idea that trunk muscle function does not directly relate to patient complaints and that CNLBP is a multifactorial issue. This model of rehabilitation programme should be used in clinical practice, as its adherence and effectiveness seem noticeable.

The role of resistance training and creatine supplementation on oxidative stress, antioxidant defense, muscle strength, and quality of life in older adults

Background

The aim of this study was to evaluate the effect of resistance training (RT) with creatine monohydrate supplementation (CS) on serum levels of 8-hydroxydeoxyguanosine (8-OHdG), malondialdehyde (MDA), glutathione peroxidase (GPX), and total antioxidant capacity (TAC) in older adults.

Objectives

This study evaluated the effect of resistance training with creatine monohydrate supplementation on oxidative stress and antioxidant defense, muscle strength and quality of life in older adults.

Methods

We examined 45 non-athlete volunteer older men and women (mean, 68.1 ± 7.2  years old), were randomly selected and divided into three groups of 15: RT with creatine supplementation (RT + CS), RT with placebo (RT + P) and control group. RT protocol was performed for 10  weeks, three sessions per week. Creatine supplement was taken daily at a dose of 0.1 g/kg of body weight, while the placebo group consumed the same amount of starch. Fasting blood samples were taken before the start of program and at the end of the RT period.

Results

In the training groups, after 10  weeks of RT, a significant decrease in MDA and 8 - OHDG as well as a significant increase in serum levels of GPX and TAC were observed (in all cases, p =  0.001). In addition, creatinine levels were enhanced in the RT + CS (p =  0.014). Training intervention also improved quality of life and muscle strength in the experimental groups (p =  0.001), although muscle strength changes were more visible in the RT + CS group than in the RT + P group (p <  0/05).

Conclusion

Regular resistance training can be recommended as a very suitable non-pharmacological approach to strengthen the body's antioxidant system, muscle strength and quality of life in older adults. There are no definite findings on the role of creatine on the antioxidant system and quality of life in older adults, but the use of this supplement in addition to RT can double the amount of strength gained from resistance training.

The Association of Body Mass Index and Fat Mass with Health-Related Physical Fitness among Chinese Schoolchildren: A Study Using a Predictive Model

Body fat mass (FM) has advantages over body mass index (BMI) in terms of accuracy of fitness assessment and health monitoring. However, the relationship between FM and fitness in Chinese children has not yet been well studied. This study aimed to investigate the relationship between health-related physical fitness, BMI, and FM, which was estimated using a predictive model among elementary schoolchildren in China. This cross-sectional study included 2677 participants (boys, 53.6%; girls, 46.4%) who underwent anthropometric measurements (height, weight, BMI, and FM) and five health-related fitness tests: 50-m sprint (speed), sit and reach (flexibility), timed rope-skipping (coordination), timed sit-ups (muscular endurance), and 50-m × 8 shuttle run (endurance). In boys, BMI showed a positive correlation with speed (p < 0.001) and endurance (p < 0.006) tests and a negative correlation with flexibility (p < 0.004) and coordination (p < 0.001) tests. In girls, a positive correlation between speed (p < 0.001) and endurance (p < 0.036) tests was observed. Both BMI and FM (estimated using the predictive model) were strongly associated with the health-related physical fitness of elementary schoolchildren. Our findings indicate that health-related physical fitness was similarly affected by FM and BMI. As FM can be quantified, it could therefore be used to develop strategies and intervention programs for the prevention and management of obesity in children.

The Effects of Traditional versus Ability-Based Physical Training on the Health and Fitness of Custody Assistant Recruits

This study investigated traditional training (TT) versus ability-based training (ABT) in custody assistant recruits. Retrospective analysis was conducted on two recruit classes who completed an 8-week academy. The TT group (18 males, 13 females) followed a physical training model where recruits completed the same exercises with the same intensity; the ABT group (17 males, 12 females) had exercises tailored towards their ability. Pre- and post-academy, recruits were assessed in: body mass; body fat percentage (BF%); resting heart rate (RHR); blood pressure (BP); waist circumference (WC); waist-to-hip ratio (WHR); grip strength; push-ups; sit-ups; YMCA step test recovery HR; 201-m run; and 2.4-km run. Independent samples t-tests evaluated between-class pre-test differences, with significance set at p ≤ 0.05. Paired samples t-tests (p ≤ 0.05) detected within-group training changes. Change scores were calculated for each variable; independent samples t-tests (p ≤ 0.05) compared change scores between groups. The TT group had lower BF%, BP, and WC; and were superior in sit-ups and the 2.4-km run before training. After academy, the TT recruits improved WHR, grip strength, recovery HR, 201-m run, and 2.4-km run, but increased diastolic BP. The ABT recruits decreased BF%, RHR, and WC, and improved push-ups, sit-ups, recovery HR, 201-m run, and the 2.4-km run. ABT recruits had greater positive changes in BF%, RHR, diastolic BP, and sit-ups. TT and ABT recruits generally experienced favorable fitness changes; the degree of positive change tended to be greater for ABT recruits for select tests. Coupled with the diastolic BP increase for TT recruits, this may provide evidence for ABT.

Body Composition and Fitness Characteristics of Firefighters Participating in a Health and Wellness Program: Relationships and Descriptive Data

This study investigated body composition and fitness test relationships from firefighters participating in a health and wellness program and categorized firefighters according to population norms relative to sex and age. Data from 270 firefighters (men = 258, women = 12) were analyzed, including body composition (body mass index [BMI], body fat percentage [BF%], waist circumference [WC], waist-to-hip ratio) and fitness (sit-and-reach, grip strength, leg press, crunches, push-ups, maximal aerobic capacity [V̇O_2max]) tests. Mann-Whitney U-test analysis (p < 0.05) showed that male firefighters had a greater WC, WHR, grip strength and leg press. Female firefighters had a greater BF% and better sit-and-reach. Partial correlations controlling for sex indicated 22/24 correlations between body composition and fitness were significant (r = -0.143--0.640). ~52% of firefighters were overweight, and 25% were Obesity Class I-III. ~76% had an increased risk of cardiovascular disease (CVD) considering BMI and WC. ~22% were fatter than average-to-overfat considering BF%. Most firefighters (73-94%) were good-to-excellent in sit-and-reach, grip strength, and push-ups; average-to-well above average in crunches; average-to-above average in leg press; and had good-to-superior V̇O_2max. Although most firefighters had better fitness compared to the general population, many had increased CVD risk. The data highlighted the need for comprehensive approaches to improving firefighter health and decreasing CVD risk.

Exploring Predictive Ability of Fitness Test Data Relative to Fire Academy Graduation in Trainees: Practical Applications for Physical Training

This study investigated the predictive abilities of fitness tests relative to academy graduation in firefighter trainees. Archival fitness test data from 305 trainees were analyzed, including: Illinois agility test (IAT); push-ups; pull-ups; leg tucks; multistage fitness test; 4.54-kg backwards overhead medicine ball throw (BOMBT); 10-repetition maximum deadlift; and a 91.44-m farmers carry with 18-kg kettlebells. Within the department, trainees were allocated points for each test. Trainees were split into graduated (245 males, 16 females) or released (29 males, 15 females) groups. Independent samples t-tests and effect sizes calculated between-group fitness test differences (raw and scaled points). To provide a binary definition for the sensitivity/specificity analysis, trainees were defined as those scoring 60+ points for a test, and those scoring 0 points. For each test, the binary result (graduated/released) was plotted against the trainee's test performance (60+ Points/0 Points). Receiver operating curves were plotted for each fitness test, and the area under the curve (AUC) determined accuracy. Trainees who graduated performed more push-ups, pull-ups, and leg tucks than released trainees, and scored more points in all tests (p≤0.005; d=0.34-1.41). Pull-ups, BOMBT, leg tuck, and the farmer's carry had high sensitivity (>80% true positive rate); the IAT had high specificity (83.3% for the true negative rate). Metronome push-ups, BOMBT points, and total points had fair accuracy for predicting academy graduation (AUC=0.709-0.754). While the data demonstrated that trainees who graduated tended to have better total-body muscular strength, endurance, and power, fitness tests may not be appropriate as a sole predictor for academy graduation.

Caffeine reverts loss of muscular performance during the early-follicular phase in resistance-trained naturally menstruating women

The aim of this study was to compare the effects of caffeine ingestion on muscular performance during the early-follicular and mid-luteal phases of the menstrual cycle. Fourteen resistance-trained naturally menstruating women performed countermovement jump (CMJ), maximal voluntary isometric contraction (MVIC), one-repetition maximum (1-RM), and repetitions-to-failure (RF) at 80% of 1-RM in the half-squat exercise, in early-follicular and mid-luteal phases, after placebo or caffeine ingestion. The early-follicular and mid-luteal phases were identified via calendar-based counting method. The MVIC was lower in the early-follicular than mid-luteal phase (-6.2 ± 15.2 N, p < 0.05) and higher with caffeine than placebo ingestion regardless of the menstrual cycle phase (+16.8 ± 26.7 N, p < 0.05). The magnitude of gains (supplement x phase interaction, p < 0.026) in 1-RM, CMJ, and RF with caffeine ingestion was higher in the early-follicular (+16.6 ± 7.1 kg, +2.5 ± 1.6 cm, and +4.5 ± 2.6 repetitions, respectively) than in the mid-luteal phase (+7.7 ± 4.8 kg, +1.5 ± 2.0 cm, and +2.4 ± 3.1 repetitions, respectively). In conclusion, the greater ergogenic effect of caffeine during the early-follicular phase supports its use to mitigate the decline in muscular performance in this phase of the menstrual cycle.

Evenness of Dietary Protein Intake Is Positively Associated with Lean Mass and Strength in Healthy Women

Background:

Evenness of protein intake is associated with increased lean mass, but its relationship with muscle strength and performance is uncertain.

Objectives:

We determined the association of evenness of protein intake with lean mass, muscle strength and endurance, and functional ability.

Design:

This was a cross-sectional study.

Setting:

Data were collected at a research university in the upper midwestern United States.

Participants:

One hundred ninety-two healthy women, aged 18 to 79 years, mean ± SEM 41.9 ± 1.3, completed the study.

Measurements:

Dietary intake was assessed using 3-day food diaries verified with food frequency questionnaires. To assess evenness of protein intake, the day was divided into 3 periods: waking to 11:30, 11:31 to 16:30, and after 16:30. Lean mass was measured with dual energy X-ray absorptiometry. Lower-body muscle strength and endurance were determined using isokinetic dynamometry. Upper-body muscle strength was maximal handgrip strength. Functional ability was assessed using 6-m gait speed and 30-second chair stand tests. Accelerometry measured physical activity.

Results:

Intakes of 25 g or more of protein at 1 or more of the 3 periods was positively associated with lean mass (β ± S.E.; 1.067 ± 0.273 kg, P < .001) and upper-body (3.274 ± 0.737 kg, P < .001) and lower-body strength (22.858 ± 7.918 Nm, P = .004) when controlling for age, body mass index, physical activity, and energy and protein intakes. Consuming at least 0.24 g/kg/period for those under 60 years and 0.4 g/kg/period for those 60 years and older was related to lean mass (0.754 ± 0.244 kg, P = .002), upper-body strength (2.451 ± 0.658 kg, P < .001), and lower-body endurance (184.852 ± 77.185 J, P = .018), controlling for the same variables.

Conclusions:

Evenness of protein intake is related to lean mass, muscle strength, and muscular endurance in women. Spreading protein intake throughout the day maximizes the anabolic response to dietary protein, benefiting muscle mass and performance.

Effects of Six-week Periodized Versus Non-Periodized Kettlebell Swing Training on Strength, Power and Muscular Endurance

The purpose of this study was to compare a periodized versus a non-periodized protocol of kettlebell (KTB) swings over six weeks on strength, power, and muscular endurance. Twenty-eight high intensity functional training (HIFT) practitioners were assigned to non-periodized (NPG = 11), periodized (PG = 11), or control groups (CG = 6). NPG used the same load (20 kg) throughout the training period while the PG used a step loading progression (with an added four kilograms every two weeks). Measures of strength and muscular endurance in the deadlift exercise, and power in the countermovement jump were assessed before and after six weeks. A two-way ANOVA was used to verify pre- to post-test differences in strength, power, and muscular endurance. An analysis of the effect size was also incorporated. For strength and power, statistical differences from pre- to post-test were found for both the NPG (p < 0.001; 1-RM improvement = 8.7%; jump height improvement = 8.7%) and PG (p < 0.001; 1-RM improvement = 7.8%; jump height improvement = 10.1%), with no difference between groups. For muscular endurance, only the PG showed significant differences from pre- to post-test (p = 0.013; muscular endurance improvement = 23.8%). In conclusion, when the goal is to increase strength and power performances in HIFT practitioners, periodized and non-periodized KTB models appear to be equally effective, and this can simplify the strength coach's practice in programming KTB swing training periods. For muscular endurance, the addition of KTB swing on a periodized basis seems to be a more effective strategy.

Effect of Brisk Walking on Health-Related Physical Fitness Balance and Life Satisfaction Among the Elderly: A Systematic Review

BACKGROUND

Although the elderly frequently engages in brisk walking as a form of exercise, little has been reported in the literature about the effect of brisk walking on health-related physical fitness, balance, and overall life satisfaction.

OBJECTIVES

The purpose of this systematic review is to determine the effect of brisk walking on the elderly's health-related physical fitness, balance, and life satisfaction.

DESIGN

We conducted a comprehensive search from the PubMed, Web of Science, Scopus, and SPORTDiscus databases from January to September 2021. We selected studies through PICOS and conducted a systematic literature review according to the PRISMA guidelines.

RESULTS

Thirteen studies met all criteria; 11 were classed as low risk of bias, while two were classified as high risk of bias. Generally, brisk walking has been shown to improve cardiorespiratory fitness, muscular strength, and body composition. Limited evidence was presented on flexibility, muscular endurance and development and life satisfaction, and there was conflicting evidence on balance. Moreover, evidence of restriction proves that high-intensity (80-85%) brisk walking is more effective than moderate-intensity (60-75%) brisk walking on the aerobic capacity of the elderly. Furthermore, there was less research conducted on males.

CONCLUSION

Brisk walking has been shown to improve cardiorespiratory fitness, muscular strength, and body composition. Other outcomes (balance, flexibility, muscular endurance, and life satisfaction) and the impact of the intensity of brisk walking on the elderly should be confirmed. Therefore, there remains insufficient research on brisk walking, while single brisk walking cannot meet requirements of elderly in terms of their health-related physical fitness, balance, and life satisfaction. Future research should aim to examine the effectiveness of combining several types of exercises to promote general health in the elderly, as the World Health Organization recommends. Unintelligible FITT (frequency, intensity, time, type) principles of brisk walking training should be trenched for the results of scientific and effective physical exercise.

High Dose of Caffeine Mouth Rinse Increases Resistance Training Performance in Men

Caffeine mouth rinsing (CMR) has been shown to enhance exercise performance. However, no studies have analyzed the effects of different dosages of CMR on muscular performance. Therefore, the purpose of this study was to examine the effects of different dosages of CMR on strength (bench press 1 repetition maximum (1-RM)) and muscular endurance (60% of 1-RM repetitions to failure) in resistance-trained males. Fourteen resistance-trained males (age: 23 ± 2 years, height: 179 ± 3 cm, body mass: 83 ± 4 kg, BMI: 17 ± 2 kg/m2) completed four conditions in random order. The four conditions consisted of a mouth rinse with 25 mL solutions containing either 1% (250 mg) of CMR (low dose of CMR: LCMR), 2% (500 mg) of CMR (moderate dose of CMR: MCMR), 3% (750 mg) of CMR (high dose of CMR: HCMR) and sweetened water (placebo: PLA) for 5 s prior to a bench press strength and muscular endurance test. Maximal strength, muscular endurance, heart rate (HR) and ratings of perceived exertion (RPE) were recorded for each condition. There were no significant differences in strength (p = 0.30) and HR (p = 0.83) between conditions. HCMR significantly increased muscular endurance performance (p = 0.01) and decreased RPE values (p = 0.01). In conclusion, CMR did not affect bench press 1-RM strength performance, but muscular endurance responses to CMR seems to be dose-dependent.

Modeling Functional Limitations, Gait Impairments, and Muscle Pathology in Alzheimer's Disease: Studies in the 3xTg-AD Mice

Gait impairments in Alzheimer's disease (AD) result from structural and functional deficiencies that generate limitations in the performance of activities and restrictions in individual's biopsychosocial participation. In a translational way, we have used the conceptual framework proposed by the International Classification of Disability and Health Functioning (ICF) to classify and describe the functioning and disability on gait and exploratory activity in the 3xTg-AD animal model. We developed a behavioral observation method that allows us to differentiate qualitative parameters of psychomotor performance in animals' gait, similar to the behavioral patterns observed in humans. The functional psychomotor evaluation allows measuring various dimensions of gait and exploratory activity at different stages of disease progression in dichotomy with aging. We included male 3xTg-AD mice and their non-transgenic counterpart (NTg) of 6, 12, and 16 months of age (n = 45). Here, we present the preliminary results. The 3xTg-AD mice show more significant functional impairment in gait and exploratory activity quantitative variables. The presence of movement limitations and muscle weakness mark the functional decline related to the disease severity stages that intensify with increasing age. Motor performance in 3xTg-AD is accompanied by a series of bizarre behaviors that interfere with the trajectory, which allows us to infer poor neurological control. Additionally, signs of physical frailty accompany the functional deterioration of these animals. The use of the ICF as a conceptual framework allows the functional status to be described, facilitating its interpretation and application in the rehabilitation of people with AD.

Effect of Functional Training on Physical Fitness Among Athletes: A Systematic Review

There is evidence that functional training is beneficial for the overall physical fitness of athletes. However, there is a lack of a systematic review focused on the effects of functional training on athletes' physical fitness. Thus, the aimed of the present review is to clarify the effects of functional training on physical fitness among athletes. In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) Statement guidelines, the systematic search of PubMed, SCOPUS, EBSCOhost (SPORTDiscus), and CINAHL Plus databases was undertaken on the 2nd November 2020 to identify the reported studies, using a combination of keywords related to functional training, physical fitness, and athletes. From the 145 studies, only nine articles met all eligibility criteria and were included in the systematic review. The assessment was performed on the Pedro scale, and the quality of the study included in the nine studies was fair (ranging from 3 to 4). The results showed that speed (n = 6) was the aspect of physical fitness studied in functional training interventions, followed by muscular strength (n = 5), power (n = 4), balance (n = 3), body composition (n = 3), agility (n = 3), flexibility (n = 1) and muscular endurance (n = 1). Existing evidence concludes that functional training significantly impacts speed, muscular strength, power, balance, and agility. Furthermore, there are still limit numbers of evidence showing effect of functional training on flexibility and muscular endurance. In contrast, no significant improvement was found in body composition where functional training was conducted. Systematic Review Registration:https://www.crd.york.ac.uk/prospero, identifier: CRD4202123092.

How Does Time Spent Working in Custody Influence Health and Fitness Characteristics of Law Enforcement Officers?

This study investigated the influence of time spent working in custody on the health and fitness of law enforcement officers (LEOs). Retrospective analysis was conducted on data from 48 male and 12 female LEOs, divided into groups based upon time spent working custody: LEO ≤ 24 (≤24 months; n = 15); LEO 2547 (25-47 months; n = 24); and LEO 48+ (≥48 months; n = 21). The following were measured: body mass index (BMI); fat mass percentage; waist-to-hip ratio (WHR); resting heart rate (RHR); blood pressure; grip strength; sit-and-reach; push-ups; sit-ups; and YMCA step test recovery heart rate (HR). A univariate ANCOVA (controlling for sex and age) with Bonferroni post hoc determined significant between-group differences. Select assessments were compared to normative data. The LEO 48+ group completed fewer sit-ups than the LEO 2547 group (p = 0.006); there were no other significant between-group differences. Forty-nine LEOs were overweight or obese according to BMI; 52 were fatter than average or above; 27 had a WHR that increased cardiovascular disease risk. Forty-three LEOs had very poor RHR; 52 had elevated blood pressure. Forty-eight LEOs had average-to-very poor step test recovery HR. Irrespective of time spent working in custody, personnel should be physically active to maintain health and fitness and, where possible, engage in formal strength training and conditioning.

Development of a Fitness Test Battery for Special Weapons and Tactics (SWAT) Operators-A Pilot Study

This investigation examined relationships between a Special Weapons and Tactics-specific fitness test (SORT) and an obstacle course (OC) used for qualification in fourteen male SWAT members from three local, regional police departments. The SORT included: squat, pushup, and lunge in 60 s; pullup hold; sled drag; and Yo-Yo Intermittent Recovery Test L1. The obstacle course included: 25 m sprint (repeated); window ascent; scale under a wall; 25 m serpentine run (repeated), body drag (20 m, repeated). Pearson coefficients examined SORT and OC relationships (p ≤ 0.05); intraclass correlation coefficients (ICC_2,1) assessed agreement of SORT trials. Repeated measures ANOVA evaluated differences in SORT metrics across time. Coefficients of variation (COV) examined SORT scoring consistency. The YoYo test was related to all SORT assessments (r = −0.803–0.894), except sled drag. The remaining SORT metrics were related to ≥two tests. SORT COVs ranged from 0.77–13.26% for trials 1–2 but decreased between trials 2–3 (0.95–8.97%). The OC was associated with YoYo, lunges, squats and sled drag (r = −0.790, −0.730, −0.766, and 0.802, respectively). No differences (p > 0.05) existed across SORT trials for event scores. The SORT battery appears to be a valid and reliable testing measure to assess SWAT occupational specific fitness.

Physical fitness: Differences between initial hiring to academy in law enforcement recruits who graduate or separate from academy

BACKGROUND

Law enforcement agencies often include fitness testing as part of the hiring process. However, it can be months from this testing to when a recruit starts academy.

OBJECTIVE

To determine fitness changes from hiring to academy in recruits who graduate (GRAD) or separate (SEP; do not complete) from academy.

METHODS

Analysis on recruits from one agency, split into GRAD (n = 436) and SEP (n = 78) groups, was conducted. These tests were conducted during initial hiring and academy: push-ups, sit-ups, and arm ergometer revolutions in 60 s; 75-yard pursuit run (75PR); and 2.4 km run. Data were analyzed via a two-way repeated measures ANOVA. Change scores were derived between hiring and academy data for both groups, and analyzed via independent samples t-tests.

RESULTS

Push-ups, 75PR, arm ergometer, and 2.4 km run generally improved (p≤0.001). There were no significant between-group interactions or differences in performance changes for GRAD and SEP recruits. SEP recruits tended to have lesser fitness test performance compared to GRAD recruits.

CONCLUSIONS

GRAD and SEP recruits showed some fitness improvements between initial hiring through to academy. However, SEP recruits with lesser muscular endurance, running speed, and aerobic capacity during hiring did not substantially improve by academy, which likely impacted their academy survivability.

With great power comes great ability: Extending research on fitness characteristics that influence work sample test battery performance in law enforcement recruits

BACKGROUND

Fitness could influence task performance in police officers. Limited research details relationships between different fitness characteristics and police-specific tasks.

OBJECTIVE

Determine relationships between anaerobic and aerobic capacity with police-specific task performance.

METHODS

Data for 308 recruits was analysed. Fitness tests included: push-ups, sit-ups, and mountain climbers (muscular endurance); pull-ups (strength); vertical jump (VJ) and 2 kg medicine ball throw (MBT; power); 75-yard pursuit run (75PR; change-of-direction speed); 201 m run (anaerobic capacity); 2.4 km run and multistage fitness test (aerobic capacity). Police tasks included: 99-yard obstacle course (99OC); 74.84 kg body drag (BD); chain link fence (CLF) and solid wall (SW) climbs; and 500-yard run (500R). Partial correlations controlling for sex and linear regression calculated relationships between fitness and job tasks.

RESULTS

99OC correlated with all assessments; BD only with 75PR. CLF related to the power and aerobic capacity tests, pull-ups, and 201 m run. SW related to VJ, 75PR, pull-ups, sit-ups, 201 m run, and aerobic capacity. 500R related to all except the MBT and 2.4 km run. 75PR and VJ predicted 4/5 tasks.

CONCLUSIONS

Police research has shown the importance of muscular endurance and aerobic capacity. Specific to this studies' correlations, the value of power and change-of-direction speed development for task performance was indicated.

Strength and endurance deficits in adults with moderate-to-severe hip osteoarthritis, compared to healthy, older adults

PURPOSE

This study compares lower limb muscle strength and endurance in adults with hip osteoarthritis, to an age-matched control group.

METHODS

Thirteen adults with moderate-to-severe hip osteoarthritis (as graded by the Oxford Hip Score) and fifteen older adults participated. Maximal voluntary isometric contraction of the knee extensors, knee flexors and hip abductors and isotonic endurance of the knee extensors were measured using a dynamometer. Function was assessed using the 30-second chair stand test, the 40 m fast-paced walk test and a stair negotiation test. Data were compared between groups using t-tests.

RESULTS

Participants with hip osteoarthritis demonstrated weakness in the affected limb when compared to the control limb during knee flexion (34%, p = 0.004) and hip abduction (46%, p = 0.001). Weakness was also observed in the contralateral knee flexors (31%, p = 0.01). When compared to the control limb, the knee extensors of the hip osteoarthritis group were exhausted prematurely in the affected (70%, p = 0.001) and contralateral limb (62%, p = 0.005). The hip osteoarthritis group took twice as long to stair climb (p = 0.002), walked 40% slower, (p < 0.001), and had a 35% lower sit-stand performance (p < 0.001).

CONCLUSIONS

Moderate-to-severe hip osteoarthritis may be characterised by bilateral deficits in lower-limb maximal strength, markedly lower knee extensor endurance and impaired functional performance.Implications for rehabilitationIn addition to bilateral deficits in maximal strength of the hip and knee muscles, moderate-to-severe hip osteoarthritis may be characterised by markedly lower muscular endurance of the knee extensors and impaired functional performance.The endurance capacity of the knee extensors can play an important role in daily function, and thus it is important to consider endurance training principles when prescribing exercise for this patient group.Research studies evaluating exercise programmes underpinned by endurance training principles are required to understand the benefits to patients with hip osteoarthritis, and to inform specific exercise prescription in clinical practice.

Analysis of the Relationship between Obesity Factors and Health-Related Physical Fitness Factors among People with Intellectual Disabilities in South Korea

Little is known about the relationship between health-related physical fitness factors and obesity-related factors in individuals with intellectual disabilities. We investigated the prevalence of obesity and the relationship between obesity-related factors and health-related physical fitness factors among people with intellectual disabilities in South Korea to identify the physical fitness factors that influence the degree of obesity. For obesity-related factors, we measured body composition (height, weight, body mass index—BMI, and body fat percentage) of 108 subjects with intellectual disabilities (mean ± standard deviation; age = 24.4 ± 8.45 years). For health-related physical fitness factors, we measured muscular strength, muscular endurance, and flexibility. There was a significant negative correlation between muscular endurance and obesity factors (BMI, r = −0.306, p < 0.01; body fat percentage, r = −0.402, p < 0.01). Further, the prevalence of obesity (34.3%) and being overweight (17.6%) among people with intellectual disabilities was high in South Korea. In addition, muscular endurance was found to have a significant effect on the obesity level (β = −0.239, p < 0.000). This suggests that a program that considers muscular endurance should be prioritized when implementing an exercise intervention strategy for the treatment of overweight and obesity among people with intellectual disabilities.

Traditional Lègong Dance Training Is Superior to Moderate Aerobic Training on Physical Fitness Improvement Among Young Girls

BACKGROUND

Légong dance is a famous Balinese dance with a dynamic movement. It potentially becomes an exercise of choice to improve young girls' physical fitness. This study aimed to evaluate légong dance training's effect on physical fitness compared with aerobic training.

METHODS

Forty young girls were randomly assigned to the aerobic training (AG) and lègong dance (DG) group and trained with jogging and lègong dancing at moderate-intensity aerobic training. Each was carried out for 30 minutes, 3 times a week, for 6 weeks.

RESULT

Aerobic capacity (estimated maximal oxygen consumption) improved significantly in AG and DG, with a mean difference and Cohen d effect size of 0.36 mL/kg/min and 0.68. The back- and leg-muscle strength increased significantly in DG and AG, with a mean difference of 5.55 kg and 6.67 kg, and an effect size of 0.69 and 0.77. Balance improved significantly in DG and AG, with a mean difference of 21.26 seconds and an effect size of 1.05. All significant values are reported at P < .05. There were no significant improvements in arm muscle strength, body fat percentage, and flexibility in either group (P > .05).

CONCLUSION

Lègong dance training results in significant physical fitness improvement and better results than aerobic training.

Estimation of Health-Related Physical Fitness Using Multiple Linear Regression in Korean Adults: National Fitness Award 2015-2019

Continuous health care and the measurement of health-related physical fitness (HRPF) is necessary for prevention against chronic diseases; however, HRPF measurements including laboratory methods may not be practical for large populations owing to constraints such as time, cost, and the requirement for qualified technicians. This study aimed to develop a multiple linear regression model to estimate the HRPF of Korean adults, using easy-to-measure dependent variables, such as gender, age, body mass index, and percent body fat. The National Fitness Award datasets of South Korea were used in this analysis. The participants were aged 19-64 years, including 319,643 male and 147,600 females. HRPF included hand grip strength (HGS), flexibility (sit and reach), muscular endurance (sit-ups), and cardiorespiratory fitness (estimated VO_2max ). An estimation multiple linear regression model was developed using the stepwise technique. The outlier data in the multiple regression model was identified and removed when the absolute value of the studentized residual was ≥2. In the regression model, the coefficient of determination for HGS (adjusted R ²: 0.870, P < 0.001), muscular endurance (adjusted R ²: 0.751, P < 0.001), and cardiorespiratory fitness (adjusted R ²: 0.885, P < 0.001) were significantly high. However, the coefficient of determination for flexibility was low (adjusted R ²: 0.298, P < 0.001). Our findings suggest that easy-to-measure dependent variables can predict HGS, muscular endurance, and cardiorespiratory fitness in adults. The prediction equation will allow coaches, athletes, healthcare professionals, researchers, and the general public to better estimate the expected HRPF.

Different Doses of Carbohydrate Mouth Rinse Have No Effect on Exercise Performance in Resistance Trained Women

Carbohydrate (CHO) mouth rinse has been shown to enhance aerobic endurance performance. However, the effects of CHO mouth rinse on muscular strength and endurance are mixed and may be dependent on dosage of CHO. The primary purpose was to examine the effects of different dosages of CHO rinse on strength (bench press 1 repetition maximum [1-RM]) and muscular endurance (40% of 1-RM repetitions to failure) in female athletes. Sixteen resistance-trained females (age: 20 ± 1 years; height: 167 ± 3 cm; body mass: 67 ± 4 kg; BMI: 17 ± 2 kg/m²; resistance training experience: 2 ± 1 years) completed four conditions in random order. The four conditions consisted of a mouth rinse with 25 mL solutions containing either 6% of CHO (Low dose of CHO: LCHO), 12% CHO (Moderate dose of CHO: MCHO), 18% CHO (High dose of CHO: HCHO) or water (Placebo: PLA) for 10 s prior to a bench press strength and muscular endurance test. Maximal strength (1-RM), muscular endurance (reps and total volume), heart rate (HR), ratings of perceived exertion (RPE) and glucose (GLU) were recorded each condition. There were no significant differences in strength (p = 0.95) or muscular endurance (total repetitions: p = 0.06; total volume: p = 0.20) between conditions. Similarly, HR (p = 0.69), RPE (p = 0.09) and GLU (p = 0.92) did not differ between conditions. In conclusion, various doses of CHO mouth rinse (6%, 12% and 18%) have no effect on upper body muscular strength or muscular endurance in female athletes.

Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum

Loading recommendations for resistance training are typically prescribed along what has come to be known as the “repetition continuum”, which proposes that the number of repetitions performed at a given magnitude of load will result in specific adaptations. Specifically, the theory postulates that heavy load training optimizes increases maximal strength, moderate load training optimizes increases muscle hypertrophy, and low-load training optimizes increases local muscular endurance. However, despite the widespread acceptance of this theory, current research fails to support some of its underlying presumptions. Based on the emerging evidence, we propose a new paradigm whereby muscular adaptations can be obtained, and in some cases optimized, across a wide spectrum of loading zones. The nuances and implications of this paradigm are discussed herein.

Ischemic Preconditioning Blunts Loss of Knee Extensor Torque Complexity with Fatigue

INTRODUCTION

Neuromuscular fatigue reduces the temporal structure, or complexity, of muscle torque output, purportedly through an effect on motor unit behavior. Ischemic preconditioning (IPC), an emerging ergogenic aid, has been demonstrated to have a potent effect on muscular output and endurance. We therefore tested the hypothesis that IPC would attenuate the fatigue-induced loss of muscle torque complexity.

METHODS

Ten healthy participants (6 males/4 females) performed intermittent isometric knee extension contractions (6 s contraction, 4 s rest) to task failure at 40% maximal voluntary contraction. Contractions were preceded by either IPC (three bouts of 5 min proximal thigh occlusion at 225 mm Hg, interspersed with 5 min rest) or SHAM (as IPC, but occlusion at only 20 mm Hg) treatments. Torque and EMG signals were sampled continuously. Complexity and fractal scaling were quantified using approximate entropy (ApEn) and the detrended fluctuation analysis (DFA) α scaling exponent. Muscle oxygen consumption (mV˙O2) was determined using near-infrared spectroscopy.

RESULTS

IPC increased time to task failure by 43% ± 13% (mean ± SEM, P = 0.047). Complexity decreased in both trials (decreased ApEn, increased DFA α; both P < 0.001), although the rate of decrease was significantly lower after IPC (ApEn, -0.2 ± 0.1 vs -0.4 ± 0.1, P = 0.013; DFA α, 0.2 ± 0.1 vs 0.3 ± 0.1, P = 0.037). Similarly, the rates of increase in EMG amplitude (P = 0.022) and mV˙O2 (P = 0.043) were significantly slower after IPC.

CONCLUSION

These results suggest that the ergogenic effect of IPC observed here is of neural origin and accounts for the slowing of the rates of change in torque complexity, EMG amplitude, and mV˙O2 as fatigue develops.

Mandatory Physical Education Classes of Two Hours per Week Can Be Comparable to Losing More than Five Kilograms for Chinese College Students

Despite releases of governmental guidelines for promoting physical fitness among the youth in China, the performance of college students in fitness tests has been declining over the past three decades. Obesity and physical inactivity have been proposed as two main causes. However, their relative importance for improving physical fitness remains unclear. To address this knowledge gap, we collected longitudinal data spanning four consecutive years on the physical fitness test for students from Nanjing University, China. Physical education classes of two hours per week were mandatory for the first two years. Using mixed effects models, we quantify the within-subject effects of weight, muscular endurance, sex, and mandatory physical education courses, among other variables, on physical fitness total score. We found that, in spite of the dominance of normal weight among the students, losing weight was positively associated with the total score, with significant sex differences in the associations. Compulsory exercise provided by physical education classes per week had strong positive impacts on the total score, comparable to losing weight of roughly 15-17 kg for males and 5-10 kg for females. Half sex difference in the total score was explained by male students' poor performance in the muscular endurance represented by pull-ups. Our results suggest that college students in China should engage in physical activity of higher levels to improve their physical fitness, with a heightened awareness of extra fat under normal weight and insufficient muscular endurance.

Caffeine increases strength and power performance in resistance-trained females during early follicular phase

The effects of 4 mg·kg^-1 caffeine ingestion on strength and power were investigated for the first time, in resistance-trained females during the early follicular phase utilizing a randomized, double-blind, placebo-controlled, crossover design. Fifteen females (29.8 ± 4.0 years, 63.8 ± 5.5 kg [mean ± SD]) ingested caffeine or placebo 60 minutes before completing a test battery separated by 72 hours. One-repetition maximum (1RM), repetitions to failure (RTF) at 60% of 1RM, was assessed in the squat and bench press. Maximal voluntary contraction torque (MVC) and rate of force development (RFD) were measured during isometric knee extensions, while utilizing interpolated twitch technique to measure voluntary muscle activation. Maximal power and jump height were assessed during countermovement jumps (CMJ). Caffeine metabolites were measured in plasma. Adverse effects were registered after each trial. Caffeine significantly improved squat (4.5 ± 1.9%, effect size [ES]: 0.25) and bench press 1RM (3.3 ± 1.4%, ES: 0.20), and squat (15.9 ± 17.9%, ES: 0.31) and bench press RTF (9.8 ± 13.6%, ES: 0.31), compared to placebo. MVC torque (4.6 ± 7.3%, ES: 0.26), CMJ height (7.6 ± 4.0%, ES: 0.50), and power (3.8 ± 2.2%, ES: 0.24) were also significantly increased with caffeine. There were no differences in RFD or muscle activation. Plasma [caffeine] was significantly increased throughout the protocol, and mild side effects of caffeine were experienced by only 3 participants. This study demonstrated that 4 mg·kg^-1 caffeine ingestion enhanced maximal strength, power, and muscular endurance in resistance-trained and caffeine-habituated females during the early follicular phase, with few adverse effects. Female strength and power athletes may consider using this dose pre-competition and -training as an effective ergogenic aid.

Carbohydrate mouth rinse improves resistance exercise capacity in the glycogen-lowered state

The effect of carbohydrate mouth rinse (CHO MR) on resistance exercise performance is equivocal and may be moderated by carbohydrate availability. This study determined the effect of CHO MR on low-load resistance exercise capacity completed in a fed but glycogen-lowered state. Twelve resistance-trained men (age: 22 ± 4 years; height: 1.79 ± 0.05 m; mass: 78.7 ± 7.8 kg; bench press one-repetition maximum (1RM): 87 ± 21 kg; squat 1RM: 123 ± 19 kg) completed two fed-state resistance exercise bouts consisting of six sets of bench press and six sets of squat to failure at 40% 1RM. Each bout was preceded by glycogen-depleting cycling the evening before, with feeding controlled to create acute energy deficit and maintain low muscle glycogen. During resistance exercise, participants rinsed with either a 6% CHO MR solution or a taste-matched placebo (PLA) between sets. Total volume workload was greater with CHO MR (9354 ± 2051 vs. 8525 ± 1911 kg, p = 0.010). Total number of repetitions of squat were greater with CHO MR (107 ± 26 vs. 92 ± 16, p = 0.017); the number of repetitions of bench press were not significantly different (CHO MR: 120 ± 24 vs. PLA: 115 ± 22, p = 0.146). This was independent of differences in feeling or arousal. CHO MR may be an effective ergogenic aid for athletes completing resistance exercise when in energy deficit and with low carbohydrate availability. Novelty: CHO MR can increase low-load resistance exercise capacity undertaken in a glycogen-lowered but fed state. This effect was driven by a greater number of repetitions-to-failure in the squat - using muscles lowered in glycogen content with exhaustive cycling on the evening prior to resistance exercise - but not bench press.

Can the Stereotype Threat and Lift Phenomenon Be Applicable to a Muscular Endurance Task?

Purpose. Inducing a negative stereotype toward women usually leads to a decrease in women performance and an increase in men performance. These effects were observed during technical tasks. The purpose of the present study was to investigate the effect of this sex stereotype during a non-technical muscular endurance task. The perception of effort, closely related to endurance performance, was also recorded. Based on the type of task and the mere effort account, we predicted that both men and women in the negative stereotype toward women condition would perform better than participants in the two other groups. Method. Seventy-seven participants (38 women and 39 men) were randomly assigned to a negative stereotype toward women, a nullified-stereotype, or a control condition. Then, they performed a submaximal handgrip task until exhaustion at 50% of their maximal strength. Results. This study showed that performance at T2 was reduced for men and women in the nullified-stereotype and control conditions, but not in the negative stereotype toward women condition, revealing that participants in the negative stereotype toward women condition performed better than participants in the other conditions. No significant difference was observed concerning the perception of effort according to the conditions. Conclusion. As compared to technical tasks, inducing a negative stereotype toward women increased women's performance. The perception of effort could be responsible for this performance improvement. However, more research is needed to investigate the mechanisms involved. Concerning men, in line with the stereotype lift phenomenon, a performance increase was observed in this same condition.

Acute Caffeine Supplementation Does Not Improve Performance in Trained CrossFit® Athletes

Caffeine's ergogenic effects persist during various exercise modalities; however, information establishing its efficacy during CrossFit^® protocols is limited. This study aimed to determine the effects of caffeine supplementation on CrossFit^® performance. Twenty CrossFit^®-trained men (age = 26.7 ± 6.2 years, experience = 3.7 ± 2.9 years) were randomized in a double-blind, crossover design. Participants completed two sessions separated by a seven-day washout period, 60 min after consuming 5 mg/kg body mass of caffeine or a placebo. In each session, participants completed as many rounds as possible in 20 min of five pull-ups, 10 push-ups, and 15 air squats. CrossFit^® performance was the total number of repetitions completed in 20 min. Paired-samples t-tests were used to compare CrossFit^® performance between caffeine and placebo conditions and to test for a potential learning effect between the first and second sessions. CrossFit^® performance was not significantly different during the caffeine condition compared to the placebo (468.6 ± 114.7 vs. 466.7 ± 94.3 repetitions, p = 0.861). A significant learning effect was identified between the first and second sessions (452.4 ± 101 vs. 483.8 ± 106.5 repetitions, p = 0.001), with no significant effect of treatment order (p = 0.438). Caffeine's ergogenic effect were not present during the CrossFit^® workout "Cindy"; however, future research should include familiarization sessions and examine other CrossFit^® workouts in novice and women participants.

A Systematic Review of Musculoskeletal Fitness Among Indigenous Populations in North America and Circumpolar Inuit Populations

BACKGROUND

North American indigenous populations experience higher rates of obesity and chronic disease compared with nonindigenous populations. Improvements in musculoskeletal fitness can mitigate negative health outcomes, but is not well understood among indigenous populations. This review examines musculoskeletal fitness measures among North American indigenous populations.

METHODS

A total of 1632 citations were evaluated and 18 studies were included.

RESULTS

Comparisons of musculoskeletal fitness measures between North American indigenous men and boys and women and girls were generally not reported. The greatest left and right combined maximal grip strength and maximal leg strength among Inuit boys and men and girls and women were observed among 20-29 years age group. Maximal combined right and left grip strength declined from 1970 to 1990, by an average of 15% among adults and 10% among youth. Maximal leg extension among Inuit has declined even further, averaging 38% among adults and 27% among youth from 1970 to 1990. Inuit men demonstrate greater grip strength and lower leg strength than Russian indigenous men, whereas Inuit women demonstrate greater leg strength.

CONCLUSIONS

Further research is needed to better understand physical fitness among indigenous peoples and the potential for improving health and reducing chronic disease risk for indigenous peoples through physical fitness.

Comparing levels of fitness of police Officers between two United States law enforcement agencies

BACKGROUND

The general physical task demands of law enforcement may suggest that police Officers are of similar fitness levels across cities, states and countries.

OBJECTIVE

To investigate whether fitness levels of police Officers from two different United States (U.S.) Law Enforcement Agencies (LEA) are similar.

METHODS

Retrospective data were analysed from two LEAs (LEA1 n = 79 and LEA2 n = 319). The data for Officers included: age, mass, 1-minute push-up repetitions, 1-minute sit-up repetitions, vertical jump height, 2.4 km run time (LEA 1) and 20-meter Multi-Stage Fitness Test results (LEA 2). Independent samples t-tests were used to compare anthropometric and fitness data between LEA with significance set at 0.05.

RESULTS

Officers from LEA1 weighed significantly less and performed significantly better than Officers from LEA2 on all fitness measures. When comparing male Officers alone, there was no statistical difference in age and mass; nonetheless, Officers from LEA1 significantly outperformed Officers from LEA2 on all fitness measures.

CONCLUSION

While similarities / differences in job tasks performed between these two LEA are not known, the results from this study suggest differences in fitness between these two different U.S. LEA. Fitness standards and training protocols need to be developed and contextualized to each LEA's specific population and needs.

Cardiorespiratory and muscular fitness in young adult Finnish men between 2003 and 2015

INTRODUCTION

Physical fitness is strongly related to health and may offer valuable information about public health. We investigated trends in physical fitness, leisure-time physical activity (LTPA), and anthropometry of young healthy adult Finnish men in representative population-based samples between 2003 and 2015.

METHODS

Three independent cross-sectional samples of 18- to 35-year-old Finnish men were assessed in 2003 (n = 889), 2008 (n = 803), and 2015 (n = 690). Cardiorespiratory (VO₂ max) and muscular fitness (1-minute sit-ups and push-ups), body mass, and height were measured. Self-reported LTPA was assessed.

RESULTS

After adjusting for age, education, and smoking, cardiorespiratory fitness was higher in 2003 (mean: 43.5, 95%CI: 42.9-44.1 mL/kg/min) compared to 2008 (41.3, 95%CI: 40.7-41.9 mL/kg/min) and 2015 (40.6, 95%CI: 40.0-41.2 mL/kg/min) (P < .001), whereas no difference was observed between 2008 and 2015. The lowest values in muscular fitness were observed in 2003, while no clear trends were further noticed. The adjusted BMI was higher in 2008 (25.1, 95%CI: 24.9-25.4) and 2015 (25.3, 95%CI: 25.3, 95%CI: 25.0-25.6) compared to 2003 (24.5, 95%CI: 24.3-24.8) (P < .005). In 2015, a higher proportion of individuals exercised at least four times per week compared to 2003 and 2008 (P < .05).

CONCLUSION

The decrease in cardiorespiratory fitness that took place between 2003 and 2008 plateaued after 2008. The plateau is in accordance with the previously observed trend of 5-10 years younger Finnish men. Moreover, muscular fitness was for the most part higher in 2008 and 2015 compared to 2003. Efforts directed to promote regular physical activity and improve physical fitness are needed.

Effects of High Intensity Interval Training on Executive Function in Children Aged 8-12 Years

This study investigated the effects of a high intensity interval training (HIIT) program on both physical fitness and executive functions in children. Fifty-six children aged 8–12 years participated in this study, and were divided into a HIIT group and a control group. The HIIT group performed three sessions of the 8- to 10-min HIIT program per week for 4 weeks. Before and after the intervention, 20-m shuttle runs, sit-ups, and standing long jumps were assessed as test of physical fitness. In addition, the executive function was assessed using the digit span forward (DSF) test, digit span backward (DSB) test, and Tower of Hanoi test. Only the HIIT group experienced significant improvement when completing the 20-m shuttle run (p = 0.042) and sit-ups (p < 0.001). Regarding executive function, the number of correct answers in DSB test significantly increased only in the HIIT group (p = 0.003). However, the standing long jump, DSF, and the Tower of Hanoi test performance did not change after intervention. The findings of the present study suggest that HIIT has positive effects on a core executive function such as working memory in addition to components of the physical fitness such as cardiorespiratory endurance and muscular endurance.

The Effects of Acute Caffeine Supplementation on Performance in Trained CrossFit Athletes

Caffeine’s ergogenic effects persist during various exercise modalities; however, information establishing its efficacy during CrossFit protocols is limited. Our study aimed to determine the effects of caffeine supplementation on CrossFit performance. Thirteen CrossFit-trained men (age = 28.5 ± 6.6 years, experience = 49.2 ± 36.3 months) were randomized in a double-blind, crossover design. Participants completed two sessions separated by a seven-day washout period, 60 min after consuming 5 mg/kg body mass of caffeine or a placebo. In each session, participants completed as many rounds as possible in 20 min of 5 pull-ups, 10 push-ups, and 15 air squats. CrossFit performance was the total number of repetitions completed in 20 min. Paired samples t-tests were used to compare CrossFit performance between caffeine and placebo conditions and to test for a potential learning effect between the first and second sessions. CrossFit performance was significantly higher during the caffeine condition compared to the placebo (461.4 ± 103 vs. 425.0 ± 93.5 repetitions, p < 0.05). No significant learning effect was identified between the first and second sessions (445.6 ± 95.0 vs. 440.8 ± 105.0 repetitions, p = 0.73) nor was there a significant treatment order effect (p = 0.40). Caffeine’s ergogenic effect is present during CrossFit; however, future investigations should establish caffeine’s efficacy during other CrossFit protocols and among female athletes.

Physical Fitness Characteristics That Relate to Work Sample Test Battery Performance in Law Enforcement Recruits

This study determined relationships between an agency-specific fitness test battery (PT500), and a work sample test battery (WSTB) in law enforcement recruits. Retrospective analysis on 219 males and 34 females from one agency was conducted. The PT500 comprised: push-ups, sit-ups, and mountain climbers in 120 s; pull-ups; and 201 m and 2.4 km runs. The WSTB comprised: 99 yard (90.53 m) obstacle course (99OC); body drag (BD) with a 165 pound (75 kg) dummy; 6 foot (1.83 m) chain link fence (CLF) and solid wall (SW) climb; and 500 yard (457.2 m) run (500R). Partial correlations, controlling for sex, calculated PT500 and WSTB relationships (p < 0.05). Stepwise regression determined whether fitness predicted WSTB performance. The 500R related to all PT500 assessments (r range = −0.127–0.574), 99OC related to all bar push-ups and mountain climbers, and BD related to none. The CLF related to sit-ups, pull-ups, and 2.4 km run; SW related to mountain climbers, pull-ups, and 2.4 km run (r range = −0.127–−0.315). Push-ups, pull-ups, and 2.4 km run were involved in predictive relationships for 99OC, CLF, SW, and 500R (r² range = 0.217–0.500). To perform better in the WSTB and job-specific tasks, developing upper-body strength and aerobic fitness may be beneficial.

Beta-Alanine Does Not Enhance the Effects of Resistance Training in Older Adults

To investigate the potential of beta-alanine to increase muscular endurance of elder individuals in specific resistance-training protocols, we randomly assigned 27 participants (60-82 years of age) to a 12-week double-blind intervention using 3.2 g/day beta-alanine or placebo with or without resistance training to determine the effects on anthropometrics, muscular performance, and activities of daily living (ADL). The endurance-based resistance-training program (ERT) was given three times per week and included two sets of 15-25 repetitions on 11 computerized pneumatic machines (alternating upper and lower body) at an intensity of 50% of maximum lifting weight (1RM). Mixed design analysis of variance (ANOVA) revealed no significant group × time interactions (p > .05) for any anthropometric or strength measures except 1RM leg press (p = .010). A post hoc analysis revealed significant improvements in 1RM leg press for both the resistance-training groups (p < .001) but no significant between-group difference attributable to beta-alanine. For the 20-repetition chest and leg press tests, no main effects of beta-alanine or group × time interactions for the exercise versus control groups were observed. Pairwise comparisons, however, did reveal significant improvements in peak and average power for both tests and fatigue index for the chest press in resistance-training groups. Although beta-alanine had no effect on any measures, the ERT program did positively affect three performance variables: 1RM, mechanical power, and fatigue patterns during muscular endurance testing. Future research should examine beta-alanine with different dosages and training programs to expand upon our findings using endurance-based resistance training.

The National Football League-225 Bench Press Test and the Size-Weight Illusion

The purpose of this study was to test reports that size and arrangement manipulations of weight plates (i.e., inducing a size-weight illusion [SWI]) effect athletic weightlifting performance. The participants were 72 experienced, weight-trained collegiate American football players. Across three weeks, each athlete performed three different repetitions-to-fatigue bench press tests (NFL-225, SWI-225, and SWI-215). A multiple regression revealed a positive association between participants' strength relative to the test load and repetitions for NFL-225 and SWI-215, but no association with SWI-225. To explore these results, players were ranked into quartiles based on their one-repetition maximum relative to 102.27 kg (225 lb), and a 3 × 4 repeated measures analysis of variance was conducted. The primary finding was a significant Test Condition × Quartile interaction ( p = .004). Bonferroni-corrected pairwise comparisons revealed that Quartile 4 (those with lowest strength relative to test load) completed more repetitions for SWI-225 compared with NFL-225 ( p = .049). These results suggest that alternate weight plate arrangements may be beneficial for those whose bench press load is near the lifter's one-repetition maximum. However, variations of the SWI do not appear to affect the performance of repetitions-to-fatigue bench press tests for the majority of collegiate American football players.

Isokinetic and Electromyographic Properties of Muscular Endurance in Short and Long-Term Type 2 Diabetes

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) are subject to progressive reduction of muscle mass and strength. The aim of this study was to assess muscle forces and electromyography (EMG) indices in short and long-term diabetes during an isokinetic exercise.

METHODS

The peak torque, work, mean power frequency (MPF) and root mean square (RMS) of knee flexors and extensors during 40 isokinetic knee extension-flexion repetitions with a velocity of 150 degree/s were recorded. 18 patients with less than 10 years with T2DM and 12 patients with equal and more than 10 years of disease were compared with 20 gender, body mass index, physical activity and peripheral circulation matched healthy controls.

RESULTS

The fatigue index and slope of line across the peak torque values of the knee flexor indicate that patients with long-term T2DM were significantly more resistant to fatigue in comparison with the two other groups (p<0.009). Whereas the MPF decrease during isokinetic protocol interact with grouping in the medial hamstring (p<0.042), but it was independent to groups in other muscles (p<0.0001). The increase of RMS after fatigue protocol interacted with sex for the medial hamstring and vastus lateralis (p<0.039) and interacted with group for the extensor muscles (p<0.045).

DISCUSSION & CONCLUSION

It seems that long-term T2DM cause some neuromuscular adaptations to maintain knee flexor muscle performance during functional activity especially postural control.

Impact of traditional Greek dancing on jumping ability, muscular strength and lower limb endurance in cardiac rehabilitation programmes

AIMS

The objective of this study was to evaluate the effect of a training programme based on traditional Greek dance on the jumping ability, muscle strength and lower limb endurance in patients with chronic heart failure (CHF).

PATIENTS AND METHODS

Forty Greek patients with CHF graded as NYHA ⩽ II and aged 73.2±4.7 years were randomly divided into two groups. Group A ( n=20) participated in a three-month physical rehabilitation programme based on Greek traditional dances, whereas group B ( n=20) remained untrained and served as the control group. All patients were studied before and after the 12-week exercise training programme. At baseline and follow-up the exercise capacity of the patients was evaluated by the six-minute walking test, their lower extremity muscle strength was evaluated by an isokinetic dynamometer and their jumping ability by the Myotest-Pro test, which includes three types of jumps (plyometric, countermovement and squat jumps).

RESULTS

No significant difference was observed between the two groups at the baseline evaluation. At follow-up, group A showed significant improvements in walking distance calculated from the six-minute walking test (10.0% improvement; p<0.05), in lower limb strength (10.32% improvement; p<0.05), and in countermovement jump speed (6.9%; p<0.05) and squat jump speed (5.8%; p<0.05). Group A also increased their jump plyometry height by 13.86% ( p<0.05), their counter jump height by 10.68% ( p<0.05) and their squat jump height by 10.45% ( p<0.05). Group A had a 6.85% ( p<0.05) increased force of counter jump compared with group B.

CONCLUSION

The design and implementation of cardiac rehabilitation programmes using Greek traditional dances in patients with CHF are both safe and effective in improving lower limb function.

Effects of Resistance Training in Youth Athletes on Muscular Fitness and Athletic Performance: A Conceptual Model for Long-Term Athlete Development

During the stages of long-term athlete development (LTAD), resistance training (RT) is an important means for (i) stimulating athletic development, (ii) tolerating the demands of long-term training and competition, and (iii) inducing long-term health promoting effects that are robust over time and track into adulthood. However, there is a gap in the literature with regards to optimal RT methods during LTAD and how RT is linked to biological age. Thus, the aims of this scoping review were (i) to describe and discuss the effects of RT on muscular fitness and athletic performance in youth athletes, (ii) to introduce a conceptual model on how to appropriately implement different types of RT within LTAD stages, and (iii) to identify research gaps from the existing literature by deducing implications for future research. In general, RT produced small-to-moderate effects on muscular fitness and athletic performance in youth athletes with muscular strength showing the largest improvement. Free weight, complex, and plyometric training appear to be well-suited to improve muscular fitness and athletic performance. In addition, balance training appears to be an important preparatory (facilitating) training program during all stages of LTAD but particularly during the early stages. As youth athletes become more mature, specificity, and intensity of RT methods increase. This scoping review identified research gaps that are summarized in the following and that should be addressed in future studies: (i) to elucidate the influence of gender and biological age on the adaptive potential following RT in youth athletes (especially in females), (ii) to describe RT protocols in more detail (i.e., always report stress and strain-based parameters), and (iii) to examine neuromuscular and tendomuscular adaptations following RT in youth athletes.

Effect of 16 weeks of resistance training on fatigue resistance in men and women

The purpose of this study was to investigate the effect of hypertrophy-type resistance training (RT) on upper limb fatigue resistance in young adult men and women. Fifty-eight men (22.7±3.7 years, 70.6±9.3 kg, and 176.8±6.4 cm) and 65 women (21.6±3.7 years, 58.8±11.9 kg, and 162.6±6.2 cm) underwent RT for 16 weeks. Training consisted of 10–12 whole body exercises with 3 sets of 8–12 repetitions maximum performed 3 times per week. Before and after the RT intervention participants were submitted to 1RM testing, as well as a fatigue protocol consisting of 4 sets at 80% 1RM on bench press (BP) and arm curl (AC). The sum of the number of repetitions accomplished in the 4 sets in each exercise was used to indicate fatigue resistance. There was a significant (p<0.05) time-by-group interaction in 1RM BP (men=+16%, women=+26%), however in 1RM AC no significant time-by-group interaction was observed (men=+14%, women=+23%). For the total number of repetitions, men and women showed a significant increase in BP (men=+16.3%, women=+10.5%) with no time-by-group interaction. The results suggest that the adaptation in maximal strength is influenced by sex in BP. On the other hand, for fatigue resistance, the individual’s sex does not seem to influence outcomes either in BP or AC.

Norms for an isometric muscle endurance test

Musculoskeletal performance assessment is critical in the analysis of physical training programs in order to prioritize goals for decreasing injury risk and focusing performance goals. Abdominal endurance as part of this analysis is often assessed with techniques that have validity that has been debated in literature. The purpose of this study was to develop normative sex- and athlete-specific percentiles for a trunk stabilization and muscular endurance by using a prone forearm plank test in college-aged students. A second purpose of this study was to investigate the effect of habitual physical activity and the reason for test termination. There were 471 participants (means ± SE; males: n = 194, age 20.4 ± 0.2 years, body height 179.4 ± 0.5 cm, body mass 81.1 ± 1.2 kg; females: n = 277, age 20.2 ± 0.2 years, body height 165.7 ± 0.4 cm, body mass 63.9 ± 0.7 kg) who performed this test to volitional or technique failure. Males produced significantly higher test durations than females (means ± SD; 124 ± 72 seconds vs. 83 ± 63 seconds) and athletes produced significantly longer test durations than non-athletes (123 ± 69 s vs. 83 ± 63 s) but no interaction effects were seen in the variables of sex and athletic status. The activity level was found to have a threshold of influence (>3 times/week) on abdominal endurance that is dose-specific where greater than 5 times/week showed the greatest influence. The fatigue of the abdominals was the termination reason producing the lowest test duration and there was no sex effect on reason for test termination. These normative percentiles for abdominal endurance suggest that the abdominal plank test can now be used as an alternative to other abdominal assessments in college students, but further investigation is warranted prior to confirmation and generalization to other populations.

Relationship between fatigue index and number of repetition maxima with sub-maximal loads in biceps curl

The aim of this study was to investigate the relationship between the number of repetition maxima to volitional failure (RM) at 60%, 75%, 90% of 1RM and fatigue index (FI), a determinant of the muscular endurance level. Thirty four resistance trained male participants attended two testing sessions. The first session was conducted to assess 1RM load and RM at 60%, 75% and 90% of 1RM in the supine biceps curl (SBC) exercise. In the second session, a FI test protocol consisting of five sets of SBC with 90 s rest between sets was performed to determine FI values. Each set was performed to volitional failure using a sub-maximal load in the range of 15-20RM. Hypothetical high FI and low FI groups (17 participants with the highest and lowest FI values, respectively) were formed for statistical analyses. ANOVA results revealed that RM at 60%, 75%, 90% of 1RM were not significantly different between FI groups when controlled for mean repetition tempo (p=0.11, p=0.38, p=0.13, respectively). Pearson’s correlation coefficients revealed that no significant relationship was present between FI values and RM at 60%, 75%, 90% of 1RM (p=0.40, p=0.46, p=0.14, respectively). In conclusion, the muscular endurance level of participants defined in terms of FI value was not an indicator of RM in SBC. Therefore, athletes with different muscular endurance levels can use similar percentages of 1RM in biceps curl exercise in their training programs when the aim is to elicit training adaptations related to specific RM zones.