Electrical Stimulation and Muscle Strength Gains in Healthy Adults: A Systematic Review.

ABSTRACT: Mukherjee, S, Fok, JR, and van Mechelen, W. Electrical stimulation and muscle strength gains in healthy adults: A systematic review. J Strength Cond Res 37(4): 938-950, 2023-Electrical muscle stimulation (EMS) is a popular method for strength gains among athletes and fitness enthusiasts. This review investigated the literature from 2008 to 2020 on EMS application protocols, strength adaptations, neural adaptations, and its use as an independent and combined training tool for strength gain in healthy adults. The investigation was modeled after the 2020 PRISMA guidelines. The eligibility criteria included studies that assessed the effect of EMS, either alone or in combination with voluntary resistance training (VRT) in healthy adult populations, involving a control group performing either usual or sham training, with at least 1 performance outcome measure assessed during experimental randomized controlled trials (RCTs), cluster RCT, randomized crossover trials, or nonrandomized studies. Ten studies met the eligibility criteria with a total of 174 subjects. Eight studies investigated the effect of EMS on lower limb muscles and 2 on elbow flexors. Five studies used concurrent VRT. Studies were heterogenous in methods, subject characteristics, intervention, and EMS protocols. All 10 studies reported significant strength gains as an outcome of EMS treatment, but there were no improvements in strength-related functional outcome measures. The optimal threshold for treatment duration, EMS intensity, pulse, and frequency could not be determined due to methodological differences and EMS application protocol inconsistency between studies. Protocol variations also existed between the studies that combined EMS with VRT. Standardized protocols are needed for electrode placement location, motor point identification, positioning of the body part being investigated, impulse type, intensity, and duration of stimulus.

Relationship of Training Load with High-intensity Running in Professional Soccer Players.

This study determined the training load (TL) and its relationship with high-intensity running performance across the season in professional soccer players. The TL, YoYo Intermittent Recovery Test Level 2 (YYIR 2) and repeated sprint ability (RSA) were monitored in 29 players (age 26.2±3.8 years, height 173.6±5.6 cm, body mass 68.5±8.6 kg). In the mid in-season (MS), Lucia TRIMP (TRIMPL) was inversely correlated with YYIR 2 (r=-0.6, p<0.05), with total distance (TD), work-rate (WR), low-intensity distance (LID) and player load (PL) showing correlation with YYIR 2 (r=0.81, 0.77, 0.88, 0.67; p<0.05) in the late in-season (LS). In pre-season (PS), TD, WR and moderate-intensity distance (MID) were correlated with YYIR 2 (r=0.65, 0.80, 0.83, p<0.05), whereas in early in-season (ES), TD, WR, LID were correlated with YYIR 2 performance (r=0.58, 0.67, 0.55, p<0.05). There was no significant relationship (p>0.05) between TL and RSA. The findings showed the volume, intensity and types of TL accrued influences the relationship with physical performance that suggest the significance of phase-specific monitoring of TL for maximizing performance in soccer players.

Combining Plant Sterols With Walking Lowers Postprandial Triacylglycerol More Than Walking Only in Chinese Men With Elevated Body Mass Index.

This study examined if plant sterols and walking reduce postprandial triacylglycerol (TAG) concentrations in Chinese men with elevated body mass index (≥ 23.5 kg/m2). Fifteen Chinese men (mean [SD]: age = 25 [3] years and body mass index = 26.2 [1.5] kg/m2] completed four 10-day trials in random order with a 7- to 10-day washout between trials: (a) daily consumption of a control margarine while sedentary (C-S), (b) daily consumption of margarine containing 2 g/day of plant sterols while sedentary (PS-S), (c) daily consumption of a control margarine with 30-min daily walking (C-W), and (d) daily consumption of margarine containing 2 g/day of plant sterols with 30-min daily walking (PS-W). On Day 11 of each trial, postprandial TAG was measured after a high-fat milkshake. The 5-hr total area under the TAG curve was 22%, 25%, and 12% lower on PS-W (mean [SD]: 8.9 [4.3] mmol·5 hr/L) than C-S (11.4 [4.5] mmol·5 hr/L; p = .005; d = 0.56), PS-S (11.9 [4.9] mmol·5 hr/L; p = .004; d = 0.67), and C-W (10.1 [4.4] mmol·5 hr/L; p = .044; d = 0.27) trials, respectively. Similarly, 5-hr incremental area for PS-W (4.5 [2.7] mmol·5 hr/L) was 31%, 32%, and 18% lower than C-S (6.6 [3.3] mmol·5 hr/L; p = .005; d = 0.62), PS-S (6.6 [3.4] mmol·5 hr/L; p = .004; d = 0.64), and C-W (5.5 [2.8] mmol·5 hr/L; p = .032; d = 0.29). Ten days of daily plant sterol intake combined with walking presents an intervention strategy to lower postprandial TAG in Chinese men with elevated body mass index.

Mobile touch screen device use and associations with musculoskeletal symptoms and visual health in a nationally representative sample of Singaporean adolescents.

This study aimed to describe contemporary technology use, especially smartphones and tablets (mobile touch screen devices), and examine associations with musculoskeletal symptoms and visual health among adolescents in Singapore. A representative sample of 1884 adolescents (50.4% girls) from grades primary 5 to post-secondary (10-18 years old), recruited from 13 schools, completed an online questionnaire in class. Total technology use was high, with smartphone duration being highest (mean = 264 [SD = 243] min/day). Patterns of use, including multitasking and bout length, were influenced by gender, school level, type of device and activities. Musculoskeletal discomfort and visual symptoms were commonly reported. After adjusting for potential confounders, more hours/day of smartphone use was associated with increased risk of neck/shoulders, upper back, arms and wrist/hand discomfort (OR = 1.04[95%CI = 1.01-1.07] to 1.07[1.03-1.10]) and visual symptoms (OR = 1.05[1.02-1.08]), but was associated with decreased odds of myopia (OR = 0.97[0.94-0.99]). No significant associations were found for tablet use. Practitioner Summary: 1884 adolescents in Singapore completed an in-depth questionnaire regarding their use of technology. The smartphone was the device with the highest usage, and greater smartphone use was associated with increased odds of musculoskeletal and visual symptoms. High use of smartphones has physical health implications for adolescents.

Developing the Singapore youth shoulder overuse injury prevention program.

OBJECTIVES: To develop the Singapore Youth Shoulder Overuse Injury Prevention Program specifically for competitive overhead youth athletes in Singapore. DESIGN: Two-round online Delphi technique with experts and a feasibility assessment questionnaire with youth athletes who represented end-users. SETTING: Volleyball for youth athletes. PARTICIPANTS: Experts were recruited through purposive sampling based on their knowledge and experience. Youth athletes were recruited though a volleyball club. MAIN OUTCOME MEASURES: The main outcome measure was the level of consensus on the proposed (1) exercise program for the overhead youth athletes, (2) education program regarding overuse injuries for coaches of overhead youth athletes, and (3) education program regarding overuse injuries for overhead youth athletes. Consensus was set at 75% agreement in this study. RESULTS: Eighteen experts completed the two Delphi rounds with 100% response rate. Consensus was achieved for the exercise program and both education programs. Twelve youth athletes completed the feasibility assessment questionnaire and found the exercises to be feasible in terms of usefulness, practical use, instructions, duration, and ease of execution. CONCLUSION: Consensus was reached for the Singapore Youth Shoulder Overuse Injury Prevention Program, and feasibility of execution by end-users was successfully determined.

Development and validation of an overuse injury questionnaire for youth athletes: The Youth Overuse Injury Questionnaire.

OBJECTIVE: To develop and validate the Youth Overuse Injury Questionnaire (YOvIQ). DESIGN: A cross-sectional study. SETTING: Online platforms. PARTICIPANTS: Two content experts (in sports injury epidemiology and in sports science and medicine) and seven end-users (youth volleyball athletes) provided feedback during development of the YOvIQ. 227 competitive youth athletes across 14 different sports assessed the psychometric properties of the YOvIQ. MAIN OUTCOME MEASURES: Participants completed both YOvIQ and the Oslo Sports Trauma Research Centre Overuse Injury Questionnaire (OSTRC-O2) for anatomical areas of the shoulder, elbow, lower back, knee, and ankle/foot. Validity was assessed via convergent validity. Reliability was assessed using internal consistency estimation and interclass correlation coefficient. RESULTS: Following feedback from content experts, examples and quantitative symbolization were added to the options in YOvIQ, with positive feedback from end-users. Convergent validity between YOvIQ and the OSTRC-O2 was demonstrated with non-significant differences (P ≥ .05) and significant correlations (P < 0.001) for prevalence and severity scores. YOvIQ demonstrated internal consistency for prevalence (Cronbach's alpha coefficient >0.70) and moderate-to-good reliability for severity scores (ICC: 0.51 to 0.88) for shoulder, lower back, and knee. CONCLUSIONS: The YOvIQ is a valid and reliable instrument to identify overuse injuries to the shoulder, lower back, and knee in youth athletes.

Traumatic upper limb injuries during the Men's Field Hockey Junior World Cup 2009.

This study was a prospective epidemiological investigation of upper limb injuries during the Men's Field Hockey Junior World Cup 2009. Three hundred twenty-four players were observed in 58 matches of the tournament. Twenty-eight upper limb-related injuries were documented. The injury incidence was 0.48 per match and 19 per 1,000 match hours. Most injuries were due to contact with the ball, and the left hand was the most commonly injured part. Contusion was the most common type of injury. The odds ratio for hand and wrist injuries in players not wearing gloves was 4.01 (95% CI, 0.52-30.62), and the relative risk of hand and wrist injuries in players wearing gloves was 0.26 (95% CI, 0.03-1.92). Male youth hockey players are at a high risk of upper limb, especially hand and wrist, injuries during major international tournaments and that use of protective gloves can provide significant protection against hand and wrist injuries in the sport.

Prevalence of Shoulder and Elbow Overuse Injuries Among Competitive Overhead Youth Athletes in Singapore.

Background: There is a dearth of information related to shoulder and elbow overuse injuries in Asian overhead youth athletes. Purpose: To determine the prevalence and severity of shoulder and elbow overuse injuries, as well as their associated factors, among competitive overhead youth athletes in Singapore. Study Design: Descriptive epidemiology study. Methods: Participants completed a survey consisting of 4 multiple-choice questions and 1 open-ended question. Data on sex, age, playing experience, and weekly training hours were also collected. Separate injury severity scores (range, 0-100, with higher scores indicating greater severity) for the shoulder and elbow were tabulated from the responses to the multiple-choice questions. The association between participant characteristics and presence of shoulder and elbow overuse injuries was determined using the chi-square test. Crude odds ratios (ORs) and 95% CIs were also calculated. Results: 532 overhead youth athletes (age, 12-18 years) responded, of which 434 responses were included for analysis. Badminton, cricket, softball, swimming, and volleyball were some of the sports studied. The prevalence of shoulder and elbow overuse injuries was 31.3% and 9.2%, respectively. The respective severity scores were 30.4 ± 14.4 and 38.4 ± 22.4. Age was associated with the presence of both shoulder (P = .016) and elbow (P = .037) overuse injuries. Years of experience was associated with the presence of substantial elbow injuries (P = .049). Weekly training hours was associated with the presence of shoulder (P = .016) and substantial shoulder (P = .020) injuries. Being older (15-18 years) increased the odds of shoulder (OR, 1.65; 95% CI, 1.10-2.49) and elbow (OR, 2.04; 95% CI, 1.03-4.01) overuse injuries. Having >8 years of experience increased the odds of substantial shoulder (OR, 2.71; 95% CI, 1.01-7.29) and substantial elbow (OR, 3.92; 95% CI, 1.01-15.24) overuse injuries. Training >11 hours per week increased the odds of shoulder overuse injuries (OR, 2.64; 95% CI, 1.31-5.30). Conclusion: Shoulder overuse injuries were more prevalent, but elbow injuries tended to be of greater severity among competitive overhead youth athletes in Singapore. Coaches working with older and experienced youth athletes, especially those training >11 hours per week, should be cognizant of the risk of shoulder and elbow overuse injuries.

Physical activity and sedentary time distribution among adult residents during COVID-19 circuit breaker movement restrictions in Singapore: a public health perspective.

Introduction: Social lockdowns and quarantines have been enforced in various populations to mitigate the spread of coronavirus disease 2019 (COVID-19) in the community. This study investigated the impact of COVID-19 lockdown, known as circuit breaker movement restrictions (CBMR), on physical activity (PA) and sedentary time (ST) distribution patterns among Singapore residents aged 21-65 years. Methods: This was a cross-sectional retrospective study that utilised a 44-item questionnaire that included sections to determine PA and ST distribution patterns before and during CBMR. It also included information on sleep duration, PA preference and routine, awareness of local initiatives and perceptions on barriers towards PA during the CBMR period. Results: There was an overall decrease in PA and a significant increase in physical inactivity and ST during the CBMR period. A greater proportion of participants reported sleeping for longer hours, suggesting positive adaptations in sleep habits during CBMR. Majority were unaware of online exercise initiatives and programmes offered during the CBMR period, and >50% of the respondents never used an online resource for exercise. Singapore residents seemed to prefer outdoor and facility-based venues for exercise and PA, and closure of facilities was the primary barrier for PA during the CBMR period. Conclusion: Reduced PA and increased ST during CBMR reflect negative lifestyle adaptations and may have adverse public health implications. Increased sleep duration suggests successful coping, which may consequently lead to physical and mental health benefits. While Singapore adult residents may be flexible with certain aspects of being physically active, they seemed less adaptive to changes in type of exercise, facility and environment.

Effectiveness of overuse injury prevention programs on upper extremity performance in overhead youth athletes: A systematic review.

Several targeted upper extremity injury prevention programs have been developed to mitigate the risk of upper extremity overuse injuries among youth athletes in overhead sports; however, their effectiveness on performance outcome measures has not been investigated. This systematic review evaluated the effectiveness of existing upper extremity injury prevention programs that focused on modifying intrinsic risk factors, and performance outcome measures in overhead youth athletes. The secondary aim was to identify the training components of these programs. PubMed, Physiotherapy Evidence Database (PEDro), SPORTDiscus (via EBSCOhost), and Web of Science were searched from January 2000 to November 2020 for studies that implemented training programs or exercises for upper extremity injury prevention among youth athletes in overhead throwing or striking sports. An updated search was conducted from December 2020 to October 2022. A program was deemed effective for a performance outcome measure if significant improvements were observed in the intervention group as compared to the control group. Of the 1 394 studies identified, five studies met the inclusion criteria. The effectiveness of the injury prevention programs on the identified performance outcome measures of strength, mobility, and sport-specific measures were 30.4%, 28.6%, and 22.2%, respectively. The training components targeted were strength, mobility, and plyometrics. Strength was the most common training component and was also the most widely investigated performance outcome measure. Overall, current upper extremity injury prevention programs seem effective at improving performance outcome measures of strength, mobility, and sport-specific outcomes with training components of strength, mobility and plyometrics. Standardized protocols are required for the measurement and reporting of performance outcomes measures, and the reporting of training components.

A prospective longitudinal study of mobile touch screen device use and musculoskeletal symptoms and visual health in adolescents.

This study aimed to examine prospective associations of mobile touch screen device (i.e. smartphone, tablet) use and patterns of use with musculoskeletal symptoms and visual health among adolescents. A representative sample of 1691 adolescents in Singapore (51% girls; 10-19 years) completed an online questionnaire at baseline and one-year follow-up. After adjusting for potential confounders, prospective associations were found between baseline smartphone use and follow-up neck/shoulder (OR = 1.61(95%CI = 1.06-2.44)) and low back (OR = 1.86(1.10-3.14)) symptoms; tablet use was also associated with neck/shoulder, low back and arms symptoms (OR = 1.33(1.04-1.71)to1.52(1.18-1.95)). No associations were observed between the duration of smartphone/tablet use and symptoms. Baseline patterns of use (bout length, certain types of activities, multitasking) were associated with follow-up musculoskeletal symptoms. Smartphone/tablet use was not related to visual outcomes (visual symptoms, wearing glasses/contact lenses, myopia) at follow-up. These findings suggest that patterns of smartphone/tablet use (though not the duration of use) can pose a prospective risk for musculoskeletal symptoms.

Fundamental Motor Skill Proficiency of 6- to 9-Year-Old Singaporean Children.

Fundamental movement proficiency (FMS) is most successfully acquired during early school years. This cross-sectional study assessed FMS proficiency in Singaporean children at the start of and following 2.5 years of primary school physical education (PE). Participants were 244 children from Primary 1 and 3 levels. Fundamental movement skills (FMS) were assessed with the Test of Gross Motor Development-Second Edition (TGMD-2) that includes locomotor (LOCO) and object control (OC) subtests. Most children were rated "average" and "below average" for LOCO skills but "poor" and "below average" for OC skills without significant gender differences on either subtest or overall FMS proficiency and without FMS mastery. These young Singaporean children failed to exhibit age-appropriate FMS proficiency despite early PE exposure, and they demonstrated lags in FMS compared with the TGMD-2 U.S. normative sample. We discuss implications for sports competence perception, difficulty in coping with later movement learning expectations and reduced later motivation to participate in PE and play. We also discuss implications for preschool and lower primary school PE curricula with a particular focus on both OC skills and LOCO skills requiring muscular fitness like hopping and jumping.

Waist circumference percentiles for Singaporean children and adolescents aged 6-17 years.

AIM: Population-specific waist circumference (WC) percentiles are crucial for screening children at higher obesity-related metabolic risk. This study aimed to develop age- and gender-specific WC percentile curves for Singaporean children and adolescents. METHODS: 3029 participants (boys, 1506; girls, 1523) from different population strata of Singapore were recruited. Stature, weight and WC were measured and BMI calculated. Smoothed WC percentile curves and cut-offs for the 3rd, 5th, 10th, 25th, 50th, 75th, 85th, 90th, 95th, 97th were constructed using the Cole's LMS method. RESULTS: WC and BMI increased with age in both sexes and boys had higher WC than girls at every age. Comparison of 50th and 90th percentiles with other populations showed distinct difference in WC curve patterns and values of Singaporean children. CONCLUSIONS: We present the first working WC percentile curves and age- and gender-specific cut-offs of Singaporean children and adolescents. These cut-offs and curves can serve as valuable reference for screening and identify children at a higher metabolic risk, for international comparisons and to better understand secular trends in paediatric obesity.

Physical Activity and Sedentary Behavior Patterns of Singaporean Adolescents.

BACKGROUND: Adolescents require at least 60 minutes of daily moderate to vigorous intensity physical activity (PA) for optimum health benefits. Reduced active and increased sedentary time can adversely affect health independently. This study investigated the sedentary behavior and physical activity patterns of Singaporean adolescents. METHODS: 233 adolescents aged 13 to 15 years participated in the study. Accelerometry was used to assess the daily PA patterns for 3 weekdays and 2 weekend days consecutively. Height, weight, BMI, waist circumference and waist-hip ratio were determined as surrogate measures of health. RESULTS: None of the participants achieved the recommended 60 minutes of daily moderate-to-vigorous physical activity (MVPA) on all 5 days. Significantly more time was spent engaging in sedentary activity compared with MVPA on both weekdays and weekends. MVPA and sedentary time were positively associated on weekdays after controlling for gender (P < .001). Weekday MVPA was positively associated with waist circumference (P < .001) and waist-hip ratio (P < .001). CONCLUSION: Singaporean adolescents fall substantially short of meeting the daily PA recommendations. Separate strategies to promote PA may be necessary for adolescents of differing weight status and gender. Pragmatic rather than idealistic targets to promote PA need to be set based on population-specific baseline data.

Injuries in Competitive Dragon Boating.

BACKGROUND: Dragon boating is a fast-growing team water sport and involves forceful repetitive motions that predispose athletes to overuse injuries. Despite the rising popularity of the sport, there is a lack of studies on injury epidemiology in dragon boating. PURPOSE: To investigate the injury epidemiology in competitive dragon boating athletes. STUDY DESIGN: Descriptive epidemiological study. METHODS: A total of 95 dragon boaters (49 males, 46 females) representing their respective universities took part in this study. Data were collected retrospectively using a reliable and valid self-report questionnaire. The study period was from August 2012 to July 2013. RESULTS: A total of 104 musculoskeletal injuries were reported (3.82 injuries/1000 athlete-exposures), 99% of which occurred during training. The most commonly injured regions were the lower back (22.1%), shoulder (21.1%), and wrist (17.3%). The majority of injuries were due to overuse (56.3%), and incomplete muscle-tendon strain was the most prevalent type of injury (50.5%). The time loss from injuries varied. In addition, a significant majority of the dragon boating athletes incurred nonmusculoskeletal injuries, with abrasions (90.5%), blisters (78.9%), and sunburns (72.6%) being the most common. CONCLUSION: Competitive dragon boating has a moderately high injury incidence, and there seems to be a direct relationship between exposure time and injury rate. A majority of the injuries are overuse in nature, and the body parts most actively involved in paddling movement are at higher risk of injuries. The high incidence of nonmusculoskeletal injuries in dragon boaters suggested that these injuries are likely outcomes of participation in the sport.

Head and face injuries during the men's field hockey Junior World Cup 2009.

BACKGROUND: Head and face injuries in field hockey are a concern. However, published data on injuries in field hockey are minimal, with apparently no reports on head and face injuries in elite youth hockey players during major international tournaments. PURPOSE: To provide a descriptive account of head and face injuries in elite youth male field hockey players during the Men's Junior World Cup 2009. STUDY DESIGN: Descriptive epidemiological study. METHODS: A total of 324 players were observed during 58 matches in the tournament. The injury reporting system was based on that used in team sports during international tournaments. All the head and face injury documentation was done by direct on-location observation by a trained sports medicine physician followed by confirmation from the team doctors or physical therapists. RESULTS: A total of 24 head and face injuries were documented. The overall injury frequency rate was 16 per 1000 match hours and 19 per 1000 player matches. There were 92% of injuries that were of contact type, with the head being the most common site and contusion being the most common type of injury. The incidence of injuries was higher during the second half and during the medal/ranking phase of the tournament. CONCLUSION: The risk of head and face injuries is high in elite youth players with a potential of both short- and long-term player time loss in international tournaments. Rigorous enforcement of rules prohibiting body contact can significantly reduce the chances of head and face injuries in elite youth field hockey players. In addition, player education on the injury risks and safe practices at the developmental stages is desirable to prevent injuries and prolong sporting careers.

Perinatal outcome in pregnancies with intra-uterine growth restriction by using umbilical and middle cerebral artery colour Doppler.

There are various biophysical methods used for diagnosing and monitoring foetal well being using in intra-uterine growth restriction foetus, out of which Doppler velocimetry proved to possess the predictive capacity in diagnosing and management of intra-uterine growth restriction foetuses. The objectives were to study Doppler velocimetry of foetal umbilical artery and middle cerebral artery in diagnosing intra-uterine growth restriction and to correlate Doppler finding with perinatal outcome. Random 50 patients with singleton pregnancies admitted in RG Kar Medical College and Hospital were studied in a duration of 1 year. Umbilical artery and middle cerebral artery were studied during foetal inactivity and apnoea. Percentage of normal and abnormal Doppler velocimetry of umbilical artery and middle cerebral artery was observed and its relation with perinatal outcome analysed. Out of 50 patients, 30% had normal and 70% had abnormal umbilical artery Doppler velocimetry. Neonatal intensive care unit admission was 20% in normal and 71.42% in abnormal umbilical artery Doppler, 46.4% in normal and 68.1% in abnormal middle cerebral artery Doppler and 9.09% in normal and 69.23% in abnormal cerebroplacental index. Neonatal mortality was 0% in normal and 14.3% in abnormal umbilical artery Doppler velocimetry. Oligohydramnios was 26% in normal and 71% in abnormal umbilical artery Doppler. The study revealed that overall perinatal outcome was poor in abnormal Doppler velocimetry group in comparison to normal group. Doppler investigation of the foetal circulation not only plays an important role in monitoring of the growth restricted foetuses but also helps in detecting foetal compromises early in intra-uterine growth restriction foetuses and thereby helps to determine the optimal time for delivery.