Musculoskeletal fitness, health outcomes and quality of life

Physical Fitness as a Predictor of Disability Retirement: A 9-Year Register Linked Follow-Up Study

BACKGROUND

To prospectively examine the association between physical fitness and risk of disability retirement in a large population-based cohort.

METHODS

This study utilized data from Health 2011 survey Physical Activity subsample (n = 4898), combined with information on disability retirement derived from 2 national registers. In total, 2455 individuals aged 18-74 years underwent the physical fitness test protocol concerning measures of cardiorespiratory fitness, muscle strength, and balance. The outcome variable was disability retirement, during the follow-up period of 9 years. After excluding those not at risk of disability retirement (ie, age ≥63 y) or who had already been granted disability pension, and those who had not completed the fitness protocol, the analytical sample included 1381 participants. Data were analyzed using Cox regression model with SPSS (version 29).

RESULTS

During the 9-year follow-up period, 61 individuals (4.4%) transitioned to a disability retirement. Cox regression analysis showed an association between the various physical fitness subdomains and the risk of disability retirement. In model 1, all fitness tests were associated with the risk of disability retirement, except the one-leg stand test with hazard ratios ranging from 1.69 (95% CI, 0.86-3.34) to 5.75 (95% CI, 1.84-17.90). Further adjustment for sociodemographic, health behavior, and health-related covariates attenuated the associations and statistical significance was lost, except for the vertical jump test (hazard ratio = 4.33; 95% CI, 1.32-14.10) and 6-minute walk test (hazard ratio = 3.81; 95% CI, 1.35-10.70).

CONCLUSION

These findings highlight the importance of physical fitness for preventing work disability.

Constitutional thinness might be characterized by physiologically adapted and not impaired muscle function and architecture: new results from the NUTRILEAN study

PURPOSE

While muscle mass and skeletal muscle fibers phenotype have been shown atypical in constitutional thinness (CT), force production capacities and its architectural determinants have never been explored. The present study compared muscle functionality and architecture between participants with CT and their normal-weight (NW) counterparts.

METHODS

Anthropometry, body composition (Dual-X-ray Absorptiometry), physical activity/sedentary behavior (ActiGraph wGT3X-BT), ultrasound recording of the Vastus Lateralis (2D-ultrasound system), and functional capacities at maximal isometric and isokinetic voluntary contractions (MVCISO and MVCCON) during knee extension (isokinetic dynamometer chair Biodex) have been measured in 18 women with CT (body mass index < 17.5 kg/m2) and 17 NW women.

RESULTS

A lower fat-free mass (ES: -1.94, 95%CI: -2.76 to -1.11, p < 0.001), a higher sedentary time, and a trend for a lower time spent at low-intensity physical activity, were observed in CT vs NW participants. While absolute MVCISO, MVCCON, rate of torque development (RTD), and torque work were all markedly lower in CT, these differences disappeared when normalized to body or muscle mass. Muscle thickness and fascicle length were found lower in CT (ES: -1.29, 95%CI: -2.03 to -0.52, p < 0.001; and ES: -0.87, 95%CI: -1.58 to -0.15, p = 0.02, respectively), while pennation angle was found similar.

CONCLUSION

Despite lower absolute strength capacities observed in CT, present findings support the hypothesis of physiological adaptations to the low body and muscle mass than to some intrinsic contractile impairments. These results call for further studies exploring hypertrophy-targeted strategies in the management of CT.

Efficacy of Lactococcus lactis subsp. lactis LY-66 and Lactobacillus plantarum PL-02 in Enhancing Explosive Strength and Endurance: A Randomized, Double-Blinded Clinical Trial

Probiotics are posited to enhance exercise performance by influencing muscle protein synthesis, augmenting glycogen storage, and reducing inflammation. This double-blind study randomized 88 participants to receive a six-week intervention with either a placebo, Lactococcus lactis subsp. lactis LY-66, Lactobacillus plantarum PL-02, or a combination of both strains, combined with a structured exercise training program. We assessed changes in maximal oxygen consumption (VO2max), exercise performance, and gut microbiota composition before and after the intervention. Further analyses were conducted to evaluate the impact of probiotics on exercise-induced muscle damage (EIMD), muscle integrity, and inflammatory markers in the blood, 24 and 48 h post-intervention. The results demonstrated that all probiotic groups exhibited significant enhancements in exercise performance and attenuation of muscle strength decline post-exercise exhaustion (p < 0.05). Notably, PL-02 intake significantly increased muscle mass, whereas LY-66 and the combination therapy significantly reduced body fat percentage (p < 0.05). Analysis of intestinal microbiota revealed an increase in beneficial bacteria, especially a significant rise in Akkermansia muciniphila following supplementation with PL-02 and LY-66 (p < 0.05). Overall, the combination of exercise training and supplementation with PL-02, LY-66, and their combination improved muscle strength, explosiveness, and endurance performance, and had beneficial effects on body composition and gastrointestinal health, as evidenced by data obtained from non-athlete participants.

Biomarkers of frailty

Several biomarkers have been proposed to identify frailty, a multisystemic age-related syndrome. However, the complex pathophysiology and the absence of a consensus on a comprehensive and universal definition make it challenging to pinpoint a singular biomarker or set of biomarkers that conclusively characterize frailty. This review delves into the main laboratory biomarkers, placing special emphasis on those associated with various pathways closely tied to the frailty condition, such as inflammation, oxidative stress, mitochondrial dysfunction, metabolic and endocrine alterations and microRNA. Additionally, we provide a summary of different clinical biomarkers encompassing different tools that have been proposed to assess frailty. We further address various imaging biomarkers such as Dual Energy X-ray Absorptiometry, Bioelectrical Impedance analysis, Computed Tomography and Magnetic Resonance Imaging, Ultrasound and D3 Creatine dilution. Intervention to treat frailty, including non-pharmacological ones, especially those involving physical exercise and nutrition, and pharmacological interventions, that include those targeting specific mechanisms such as myostatin inhibitors, insulin sensitizer metformin and with special relevance for hormonal treatments are mentioned. We further address the levels of different biomarkers in monitoring the potential positive effects of some of these interventions. Despite the availability of numerous biomarkers, their performance and usefulness in the clinical arena are far from being satisfactory. Considering the multicausality of frailty, there is an increasing need to assess the role of sets of biomarkers and the combination between laboratory, clinical and image biomarkers, in terms of sensitivity, specificity and predictive values for the diagnosis and prognosis of the different outcomes of frailty to improve detection and monitoring of older people with frailty or at risk of developing it, being this a need in the everyday clinical practice.

Muscular fitness profiles in relation to the response in body fat during school-based high-intensity intervention

BACKGROUND

We aimed to assess the equivalence of the muscular fitness (MF) between body fat percentage (BFP) responders (RsBFP) and non-responders (NRsBFP) to school-based high-intensity interval training (HIIT). Adolescents aged 16 (N.=73, 42.5% of males) were identified as RsBFP (N.=45) or NRsBFP (N.=28). MF was assessed based on hand strength (HS), abdominal muscle strength (ABS), and leg power (VJ).

METHODS

Profile analysis showed distinct patterns of MF changes in both response categories. Despite the presence of parallelism (Wilks' Λ=0.979, Pillai's V=0.212, P=0.473), a gradient of increasing changes (HS-ABS-VJ) was found in the RsBFP, while a gradient of decreasing changes was shown in the NRsBFP, and a significant level of inequality (F(1,71)=7.823, P=0.047, partial eta-squared [η2p] 0.041).

RESULTS

One-way analysis showed a significant and moderate effect on VJ (F(1,71)=7.080, P=0.010, η2P=0.091), a close to significant effect on ABS (F(1,71)=3.300, P=0.074, η2P=0.044) and lack of an effect on HS (F(1,71)=0.699, P=0.406, η2P=0.010). The test of equal means across the condition categories (separately for RsBFP and NRsBFP) indicated that there was no multivariate statistically significant within-group effect (F(2, 70)=0.517, P=0.599).

CONCLUSIONS

The findings may help teachers assess the potential and indirect changes in muscle performance after employing a body weight intervention (based on the HIIT program). A more targeted approach to treating adolescents with excessive BF, in parallel with improving MF, can be individually tailored.

Effects of plyometric training on health-related physical fitness in untrained participants: a systematic review and meta-analysis

Plyometric training (PT) is an effective training method for improving physical fitness among trained individuals; however, its impact on health-related physical fitness in untrained participants remains ambiguous. Therefore, this meta-analysis aimed to evaluate the effects of PT on health-related physical fitness among untrained participants. Six electronic databases (PubMed, CINAHL Plus, MEDLINE Complete, Web of Science Core Collection, SCOPUS, and SPORTDiscus) were systematically searched until March 2024. We included controlled trials that examined the effects of PT on health-related physical fitness indices in untrained participants. Twenty-one studies were eligible, including a total of 1263 participants. Our analyses revealed small to moderate effects of PT on body mass index, muscular strength, cardiorespiratory fitness, and flexibility (ES = 0.27-0.61; all p > 0.05). However, no significant effects were detected for body fat percentage and lean mass (ES = 0.21-0.41; all p > 0.05). In conclusion, the findings suggest that PT may be potentially effective in improving health-related physical fitness indices (i.e., body mass index, muscular strength, cardiorespiratory fitness, and flexibility) in untrained participants. However, the results should be interpreted cautiously due to data limitations in some fitness variables.

Musculoskeletal and cardiovascular considerations for transgender athletes

OBJECTIVE

Participation in athletics is essential for the overall well-being of transgender athletes and should be included as part of gender-affirming care. Surveys show physicians and athletic trainers want to provide appropriate care for transgender athletes but lack the proper knowledge and training to do so. Gender Affirming Hormone Therapy (GAHT) is part of gender-affirming care, yet the effects of GAHT on the cardiovascular and musculoskeletal health of transgender athletes is not well-understood. The purpose of this review was to discuss important musculoskeletal and cardiovascular considerations unique to transgender athletes and improve physician understanding in caring for transgender athletes.

METHODS

A representative selection of literature on the effects of GAHT on cardiovascular and musculoskeletal health was included in this review.

RESULTS

Estrogen therapy may increase the risk of venous thromboembolism (VTE) and stroke, and decrease blood pressure levels among transgender women, while studies on lipid profile are inconsistent among both transgender men and women. Transgender women receiving GAHT may also be at greater risk for bone fracture and ligamentous injuries.

CONCLUSION

Exercise is essential for the well-being of transgender individuals and special considerations regarding the cardiovascular and musculoskeletal health of transgender athletes should be incorporated into standard medical education. Educational programs for transgender patients and their support team should focus on preventative measures that can be taken to reduce the risk of adverse musculoskeletal and cardiovascular events. The PPE is an invaluable tool available to physicians to monitor the health and safety of transgender athletes and should be regularly updated as research on the health of transgender individuals continues to grow. Longitudinal and prospective studies should examine the effects of GAHT on the musculoskeletal and cardiovascular health of transgender athletes. Lastly, health care providers play an important role in the advancement of gender-neutral policies.

Influence of short bouts of stair climbing on young adults during prolonged sitting on posture, discomfort, and musculoskeletal performance outcomes: a counterbalanced pilot randomised crossover trial

Prolonged sitting is postulated to influence musculoskeletal performance (cervical flexor endurance, balance, and agility), discomfort and alter cervical spine angles during work-based computer use. Stair climbing breaks may be a great addition at typical and home offices however remain unexplored for its impact on musculoskeletal performance. In our counterbalanced pilot crossover trial, 24 adults were randomised to three interventions: (1) prolonged sitting, (2) interrupted by 2 min of self-paced, and (3) externally paced stair climbing for 2 h. Cervical spine angles were measured every 30 min while balance, agility, endurance, and discomfort were assessed before and after 120 min. Stair climbing interruptions have favourable effects on agility (F = 8.12, p = 0.009, ηp2 = 0.26) and musculoskeletal discomfort, but failed to improve other musculoskeletal outcomes associated with prolonged sitting. Brief stair climbing interruptions are effective in improving discomfort and agility while pragmatic trials are warranted for translated effects.

Effects of thumb-tack needling combined with sporting on older adult patients with knee osteoarthritis: A randomized active-control clinical trial

AIM

The aim of this clinical study was to explore the effects of thumb-tack needling combined with sporting (TTNS) therapy on the improvement of pain and joint function in older adult patients with knee osteoarthritis (KOA).

METHODS

A total of 120 older adult patients with KOA were randomly assigned to receive TTNS therapy or medicine treatment (Med group) only for 1 month. The patients were followed up for 3 months and clinical efficacies were evaluated using a visual analog scale to assess pain, the Lequesne scoring system to assess motor function, and the Western Ontario and McMaster University Osteoarthritis Index to assess KOA severity. Blood was collected to measure the levels of interleukin-6 and tumor necrotic factor-alpha using enzyme-linked immunosorbent assay.

RESULTS

The data suggested that TTNS therapy resulted in a significantly higher clinical efficacy (P = 0.012). Visual analog scale score, Lequesne index, and Western Ontario and McMaster University Osteoarthritis Index of the TTNS group at the time of post-treatment (1 month) and post-follow-up (3 months) were also lower compared with the Med group. Patients in the TTNS group also showed lower levels of serum tumor necrotic factor-alpha and interleukin-6.

CONCLUSIONS

TTNS therapy is more efficacious than pharmacological treatment in improving the clinical outcomes of patients with KOA, which suggests its clinical utility in the management of KOA. Geriatr Gerontol Int 2024; 24: 415-420.

Resistance exercise snacks improve muscle mass in female university employees: a prospective, controlled, intervention pilot-study

Background

Although resistance training (RT) is essential to preserve musculoskeletal fitness and maintain a healthy, independent life into old age, few women perform RT. We investigated whether resistance exercise snacking (RES) could be an efficient training approach for the workplace health promotion (WHP) to minimize barriers for participation and facilitate RT in women in order to improve musculoskeletal fitness.

Methods

This pilot-study followed a prospective, controlled intervention design. Female employees with sedentary occupations doing RT on less than 2 days/week before study participation were included. Participants self-selected for either intervention (IG) or control group (CG). While the IG [N = 15, mean age 42.1 (SD = 11.1) years] did 10 min of RES on working days for 12 weeks, the CG [N = 15, mean age 49.9 (SD = 9.7) years] was instructed to maintain their habitual physical activity. Primary endpoint was change in muscle mass. Secondary endpoint was change in maximum isometric strength. Balance, cardiovascular fitness, perceived health, and general life satisfaction was assessed for exploratory purpose. Measurements were taken before and after the intervention.

Results

12 participants of IG and 14 of CG completed the study. Muscle mass improved significantly more in the IG [+0.42 (SD = 0.54) kg] compared to the CG [-0.16 (SD = 0.51) kg] (p = 0.01, ƞ2p = 0.24). Strength did not change significantly between groups. Nevertheless, there was a trend for greater improvements in the IG compared to the CG for trunk extension, trunk flexion, and upper body push but not upper body pull. Regarding exploratory endpoints, no significant between-group changes were found. Despite their poor fitness, both groups perceived their health as good and had high life satisfaction before and after the intervention.

Conclusion

RES could be an effective approach for the WHP to promote RT in inactive women with sedentary occupations and improve their muscle mass.

Association between fitness technology use and physical activity mediated by communication behaviors on social media

Objective

Fitness technologies, such as smartphone applications and wearable tracking devices, have gained widespread popularity. This study had two main objectives: 1) to examine whether fitness technology use is associated with increased physical activity (PA) levels and 2) to investigate whether communication behaviors on social media mediated the association between fitness technology use and PA.

Methods

Data were from the U.S. Health Information National Trends Survey 2022 (N = 6,252, weighted N = 258,418,467). Weighted linear regressions were conducted to examine the associations between fitness technology usage, physical activities, and communication behaviors on social media. Mediations were tested using PROCESS macro, a path-analysis based tool.

Results

Controlling for demographic and other known influences on PA, the findings revealed that users of fitness technology reported higher levels of both moderate PA (β = .41, p < 0.001) and strength training (β = .29, p < 0.001). Additionally, communication behaviors (i.e., sharing personal health information on social media and watching health-related videos on social media) mediated the relationship between fitness technology use and frequencies of strength training.

Conclusion

The results underscored the potential of fitness technologies in enhancing PA levels through promoting communication behaviors on social media.

The effect of back muscle fatigue on EMG and kinematics based estimation of low-back loads and active moments during manual lifting tasks

This study investigated the effects of back muscle fatigue on the estimation of low-back loads and active low-back moments during lifting, using an EMG and kinematics based model calibrated with data from an unfatigued state. Fourteen participants performed lifting tasks in unfatigued and fatigued states. Fatigue was induced through semi-static forward bending. EMG, kinematics, and ground reaction forces were measured, and low-back loads were estimated using inverse dynamics and EMG-driven muscle model. A regression model was developed using data from a set of calibration lifts, and its accuracy was evaluated for unfatigued and fatigued lifts. During the fatigue-inducing task, the EMG amplitude increased by 2.8 %MVC, representing a 38% increase relative to the initial value. However, during the fatigued lifts, the peak EMG amplitude was found to be 1.6 %MVC higher than that observed during the unfatigued lifts, representing a mere 4% increase relative to the baseline unfatigued peak EMG amplitude. Kinematics and low-back load estimates remained unaffected. Regression model estimation errors remained unaffected for 5 kg lifts, but increased by no more than 5% of the peak active low-back moment for 15 kg lifts. We conclude that the regression-based estimation quality of active low-back moments can be maintained during periods of muscle fatigue, although errors may slightly increase for heavier loads.

Effects of Muscular Strength Training on Oral Health and Quality of Life: Using Korean Panel Survey Data, a Cross-Sectional Study

OBJECTIVES

The purpose of this study is to confirm the importance of muscular strength exercise by confirming the relationship between strength exercise, oral health, and quality of life.

METHODS

Using the 2019 and 2021 of the Korean National Health and Nutrition Examination Survey (KNHANES), 6535 people were selected as subjects. Complex sampling analysis was applied to all analyses; 2267 people were in the muscular strength training group (MSG), and 5841 people were in the non-muscular strength training group (NMSG). A multi-sample linear regression analysis was conducted to confirm the effect of muscular strength training on oral health and quality of life.

RESULTS

As a result of confirming the effect of muscular strength training on oral health status, problems with chewing decreased by 0.105, and problems with speaking decreased by 0.028 with MSG compared to NMSG. In addition, compared to NMSG, it was confirmed that MSG reduced chewing discomfort by 0.047, while self-perceived oral health improved by 0.0123. Finally, as a result of confirming the effect of muscular strength training on oral health and quality of life in Korean adults, there was a significant effect on quality of life despite adjusting for sociodemographic characteristics and oral-health-related factors (p < 0.05).

CONCLUSIONS

In this study, the relationship between muscular strength training and quality of life was confirmed. Therefore, efforts should be made to make oral health management and muscular strength training a part of life in relation to quality of life.

Analysis of Self-Perceived Physical Fitness of Physical Education Students in Public Schools in Extremadura (Spain)

Adolescence is a stage of crucial physiological and psychological changes within the individual's life cycle, where fitness work is important. With self-perception being crucial in relation to adolescent health and well-being, a positive perception of fitness is directly related to increased practice or higher level of physical activity (PA). Thus, the aims were: (1) to analyze, with the Visual Analogue Fitness Perception Scale for Adolescents (FP VAS A), the self-perceived physical fitness (PF) of high school students, (2) to investigate if there are differences according to sex and school location, and (3) to study the correlations between the items of the FP VAS A with age and body mass index (BMI). For this purpose, a cross-sectional study was designed with a total of 961 participants, 48.8% boys and 51.2% girls in secondary education, where 31.9% studied in rural schools and 68.1% in urban schools. The FP VAS A scale was used to assess self-reported PF. Regarding the results, there were statistically significant differences between sexes (p < 0.001), with boys showing higher scores than girls in all the items of the FP VAS A scale, with the exception of global flexibility. Inverse, mean and significant correlations were established between BMI and self-perceived overall PF (r = -0.202; p < 0.001), cardiorespiratory endurance (r = -0.226; p < 0.001) and movement speed (r = -0.268; p < 0.001). Between age and self-perceived cardiorespiratory endurance (r = -0.138; p < 0.001) an inverse, mean and significant correlation was also observed. In conclusion, boys showed a better self-perception of PF than girls for all physical abilities, with the exception of flexibility. School location was not shown to influence students' self-perceived PF. In addition, most of the self-perceived PF abilities for overall fitness correlated inversely with BMI.

Increasing Muscle Mass in Elders through Diet and Exercise: A Literature Review of Recent RCTs

This study aimed to review the current evidence on the independent and combined effects of diet and exercise and their impact on skeletal muscle mass in the elderly population. Skeletal muscle makes up approximately 40% of total body weight and is essential for performing daily activities. The combination of exercise and diet is known to be a potent anabolic stimulus through stimulation of muscle protein synthesis from amino acids. Aging is strongly associated with a generalized deterioration of physiological function, including a progressive reduction in skeletal muscle mass and strength, which in turn leads to a gradual functional impairment and an increased rate of disability resulting in falls, frailty, or even death. The term sarcopenia, which is an age-related syndrome, is primarily used to describe the gradual and generalized loss of skeletal muscle mass (mainly in type II muscle fibers) and function. Multimodal training is emerging as a popular training method that combines a wide range of physical dimensions. On the other hand, nutrition and especially protein intake provide amino acids, which are essential for muscle protein synthesis. According to ESPEN, protein intake in older people should be at least 1 g/kgbw/day. Essential amino acids, such as leucine, arginine, cysteine, and glutamine, are of particular importance for the regulation of muscle protein synthesis. For instance, a leucine intake of 3 g administered alongside each main meal has been suggested to prevent muscle loss in the elderly. In addition, studies have shown that vitamin D and other micronutrients can have a protective role and may modulate muscle growth; nevertheless, further research is needed to validate these claims. Resistance-based exercise combined with a higher intake of dietary protein, amino acids, and/or vitamin D are currently recognized as the most effective interventions to promote skeletal muscle growth. However, the results are quite controversial and contradictory, which could be explained by the high heterogeneity among studies. It is therefore necessary to further assess the impact of each individual exercise and nutritional approach, particularly protein and amino acids, on human muscle turnover so that more efficient strategies can be implemented for the augmentation of muscle mass in the elderly.

Use of Lower Limb Exoskeletons as an Assessment Tool for Human Motor Performance: A Systematic Review

Exoskeletons are a promising tool to support individuals with a decreased level of motor performance. Due to their built-in sensors, exoskeletons offer the possibility of continuously recording and assessing user data, for example, related to motor performance. The aim of this article is to provide an overview of studies that rely on using exoskeletons to measure motor performance. Therefore, we conducted a systematic literature review, following the PRISMA Statement guidelines. A total of 49 studies using lower limb exoskeletons for the assessment of human motor performance were included. Of these, 19 studies were validity studies, and six were reliability studies. We found 33 different exoskeletons; seven can be considered stationary, and 26 were mobile exoskeletons. The majority of the studies measured parameters such as range of motion, muscle strength, gait parameters, spasticity, and proprioception. We conclude that exoskeletons can be used to measure a wide range of motor performance parameters through built-in sensors, and seem to be more objective and specific than manual test procedures. However, since these parameters are usually estimated from built-in sensor data, the quality and specificity of an exoskeleton to assess certain motor performance parameters must be examined before an exoskeleton can be used, for example, in a research or clinical setting.

Hybrid-type, multicomponent interval training upregulates musculoskeletal fitness of adults with overweight and obesity in a volume-dependent manner: A 1-year dose-response randomised controlled trial

This study examined the dose-response effects of a 1-year hybrid-type, multicomponent interval training programme (DoIT) on various musculoskeletal fitness parameters in inactive overweight and obese adults in a gym setting. Ninety-seven middle-aged (44.8 ± 5.2 years) individuals with overweight/obesity (31.2 ± 5.7 kg/m²) (66% female) were randomly assigned to the following groups: (i) no-intervention control (CON, n = 29), (ii) DoIT performed once weekly (DoIT-1, n = 24), (iii) DoIT performed twice weekly (DoIT-2, n = 23) and (iv) DoIT performed thrice weekly (DoIT-3, n = 21). DoIT was a time-efficient, intermittent-based, multicomponent exercise protocol using progressive loaded fundamental movement patterns with prescribed work-to-rest intervals (1:3-2:1) in a circuit format (2-3 rounds). Muscular strength, muscular endurance, flexibility, passive range of motion (PRoM), static balance and functional movement screen (FMS®) were assessed at baseline, 6 and 12 months following intervention. At post-training, all exercise groups exhibited superior changes than CON in (i) muscular strength (+13%-38%, p < 0.001); (ii) muscular endurance (+42%-159%, p < 0.001); (iii) flexibility (+12%-42%, p < 0.001); (iv) PRoM (+6%-50%, p = 0.001-0.026); (v) static balance (+61%-163%, p < 0.001); and (vi) FMS (+18%-39%, p < 0.001). Although a single exercise session/week improved musculoskeletal fitness, changes demonstrated a step-wise improvement with two and three sessions/week suggesting a dose-dependent response. The response rate to training was 100% for all exercise groups. These findings suggest that a multicomponent exercise approach incorporating bodyweight drills and resistance-based alternative modes performed under real-world conditions may improve several musculoskeletal fitness indicators in a dose-dependent manner in inactive, middle-aged adults with overweight/obesity.Trial registration: ClinicalTrials.gov identifier: NCT03759951.

Clustered Associations between Musculoskeletal Fitness Tests and Functional Movement Screen in Physically Active Men

Functional Movement Screen (FMS) is a tool used to assess fundamental movement patterns. There are relationships between musculoskeletal fitness (MSF) and a FMS. However, there is limited data regarding the multidimensional associations between these two constructs. This study is aimed at investigating the associations and detailed structures of FMS components and MSF components and identifying a deeper detailed structure of their relations to physical fitness. The study sample included 114 physically active men with an average body height of 1.81 ± 0.07 (cm), body weight of 80.61 ± 9.49 (kg), and a BMI of 24.65 ± 2.46 (kg/m²). Each participant performed a FMS test, sit-and-reach (S&R) test, sit-ups (ABS) evaluation, balance evaluation on an AMTI platform, handgrip strength (HG) testing, and standing broad jump (SBJ) ability. The Kendall's Tau correlation was performed to identify simple associations between FMS and MSF. Cluster analysis was used to determine the multidimensional nature of the relationships. In the vast majority, a positive correlation was observed suggesting that a high level of MSF improved FMS test results. A cluster analysis revealed 4 separate clusters. Shoulder mobility (SM) was identified as a single cluster. A strong similarity was observed between SBJ and trunk stability push-up (TSPU) forming a second cluster. This cluster joined to another consisting of the S&R test and active straight leg raise (ASLR) test. The last cluster consisted of HG and hurdle step (HS). These results confirmed that FMS and MSF tests measure the same constructs-a foundation for an individual's motor coordination, muscle strength, postural stability, and dynamic balance. This knowledge could be helpful in effectively enhancing physical performance based on combining similar constructs to accelerate the achievement of established goals.

Effect of resistance training on local muscle endurance in middle-aged and older adults: A systematic review with meta-analysis and meta-regression

BACKGROUND

Local muscle endurance (LME) is a significant indicator of muscle health and function in middle-aged and older adults. However, resistance training (RT) practices which optimise performance in this population are currently unclear. This study examined: 1) the effect of RT on LME; and 2) the impact of acute resistance exercise program variables on LME in middle-aged and older adults.

METHODS

Five electronic databases were searched using terms related to RT, LME, and older adults. Random effects (Hedges' g) meta-analyses were undertaken to estimate the effect of RT on upper and lower body LME assessed via maximal repetitions during an isotonic test. The impact of resistance exercise program variables on LME effects was explored using meta-regression analyses.

RESULTS

Fifteen studies met the inclusion criteria for this review. Upon sensitivity analysis, one study was removed. Large effects favoured RT for LME of the upper body (g = 1.10, p < 0.001) and lower body (g = 1.18, p < 0.001). Large effects on LME from RT were found irrespective of training intensity or other resistance exercise program variables. Moderate heterogeneity and publication bias were found in most analyses.

DISCUSSION

RT is an effective means for improving LME in middle-aged and older adults. Optimal training characteristics have not been defined by this review, as improvement in LME was unrelated to RT volume or loading intensity. Caution is warranted when interpreting the findings due to heterogeneity and bias present in existing literature. Additional studies are needed with direct comparisons of various training techniques.

Cross-sectional and longitudinal associations between body flexibility and sarcopenia

BACKGROUND

The associations between body flexibility and sarcopenia were not well understood. This study aimed to explore the cross-sectional and longitudinal associations of flexibility with sarcopenia.

METHODS

Our study selected participants aged 50-80 from the WELL-China cohort and the Lanxi cohort. Participants from the urban area of the Lanxi cohort were followed up 4 years later. Body flexibility was measured by the sit-and-reach test. Muscle mass was evaluated by dual-energy X-ray absorptiometry. Muscle strength was evaluated using handgrip strength. Sarcopenia was defined as having both low muscle mass and low muscle strength. We used multivariable logistic regressions to assess the cross-sectional associations of body flexibility with low muscle mass, low muscle strength and sarcopenia. We also used multivariable logistic regressions to explore the associations of baseline flexibility and 4-year changes in flexibility with incident low muscle mass, low muscle strength and sarcopenia.

RESULTS

A total of 9453 participants were enrolled in the cross-sectional study, and 1233 participants were included in the longitudinal analyses. In the cross-sectional analyses, compared with low body flexibility, high body flexibility was inversely associated with low muscle mass (odds ratio [OR], 0.58; 95% confidence interval [CI], 0.50-0.68; P < 0.001), low muscle strength (OR, 0.62; 95% CI, 0.55-0.69; P < 0.001) and sarcopenia (OR, 0.52; 95% CI, 0.41-0.65; P < 0.001), and these associations did not differ in different age groups, sex or physical activity levels. In the longitudinal analyses, compared with participants with low body flexibility, participants with high body flexibility had lower risk of the incident low muscle strength (OR, 0.53; 95% CI, 0.38-0.74; P < 0.001) and sarcopenia (OR, 0.36; 95% CI, 0.21-0.61; P < 0.001), but not incident low muscle mass (OR, 0.59; 95% CI, 0.33-1.06; P = 0.076). Every 1-cm increase in flexibility during 4 years was associated with reduced risk of incident low muscle mass (OR, 0.96; 95% CI, 0.93-1.00; P = 0.025), low muscle strength (OR, 0.96; 95% CI, 0.94-0.98; P = 0.002) and sarcopenia (OR, 0.96; 95% CI, 0.93-0.99; P = 0.007).

CONCLUSIONS

High flexibility was associated with reduced risk of incident low muscle strength and sarcopenia. Increases in flexibility were associated with reduced risk of incident low muscle mass, low muscle strength and sarcopenia. Flexibility exercises and monitoring the dynamic change of flexibility might be helpful in preventing sarcopenia among adults aged 50 years or over.

The association between muscle strength and executive function in children and adolescents: Based on survey evidence in rural areas of China

Background

In recent years, muscle strength in children and adolescents has continued to decline, especially in rural areas. Executive function as a higher function of the brain, is closely related to the future achievement of children and adolescents. For this reason, this study analyzed the correlation between muscle strength and executive function in children and adolescents in rural areas of China to better promote the development of muscle strength and executive function.

Methods

Demographic factors, muscle strength, and executive function were tested in 1,335 children and adolescents in rural China using a three-stage stratified whole-group sampling method. One-way ANOVA and chi-square test were used to compare the differences in executive function among children and adolescents with different muscle strengths. Multiple linear regression analysis and logistic regression analysis were used to analyze the association that exists between muscle strength and executive function.

Results

When comparing the inconsistently, congruent, 1back, 2back, conversion, size parity, and cognitive flexibility response times of children and adolescents with different muscle strength indexes in rural China, the differences were statistically significant (F = 46.592, 45.610, 10.809, 32.068, 24.095, 19.260, 11.501, p < 0.001). Logistic regression analysis was performed using children and adolescents with muscle strength index >P80 as the control group. The results showed that the risk of 1back dysfunction was higher (OR = 1.764, 95% CI:1.094, 2.843) in children and adolescents with muscle strength index <P20 (p < 0.05). The risk of 2back dysfunction was higher in children and adolescents with a muscle strength index <P20 (OR = 2.129, 95% CI:1.329, 3.410) (p < 0.01). Compared with children and adolescents with muscle strength index >P80. The muscle strength index <P20 group had a higher risk of cognitive flexibility dysfunction (OR = 1.820, 95% CI:1.111, 2.982) (p < 0.05).

Conclusion

There is a association between muscle strength and executive function in children and adolescents in rural areas of China. Those with higher muscle strength have shorter executive function reaction times and are at lower risk of developing executive dysfunction. Future measures should be taken to improve muscle strength and executive function levels in children and adolescents in rural areas to promote healthy physical and mental development.

Characterization of muscle recruitment during gait of bilateral transfemoral and through-knee persons with limb loss

Introduction: Due to loss in musculoskeletal capacity, there is an increased burden on the residual limbs of bilateral transfemoral and through-knee persons with limb loss. This reduced capacity is associated with an increased cost of walking that is detrimental to functionality. Compensatory gait strategies are adopted by this population. However, how these strategies relate to specific muscle recruitment is not known. The primary aim of this study is to characterize muscle recruitment during gait of this population. The secondary aim is to assess whether the measured kinematics can be actuated when the endurance of specific muscles is reduced and if this is the case, which alternative muscles facilitate this. Methods: 3D gait data and high-resolution magnetic resonance images were acquired from six bilateral transfemoral and through-knee persons with limb loss. Subject-specific anatomical muscle models were developed for each participant, and a validated musculoskeletal model was used to quantify muscle forces in two conditions: during normal gait (baseline) and when muscles, which were identified as functioning above a "healthy" level at baseline, have a reduced magnitude of maximum force capacity (reduced endurance simulation). To test the hypothesis that there are differences in muscle forces between the baseline trials and the simulations with reduced muscular endurance, a Bonferroni corrected two-way ANOVA with repeated measures was completed between the two states. Results: The baseline analysis showed that the hip flexors experience relatively high muscle activations during gait. The reduced endurance simulation found two scenarios. First, for 5 out of the 12 simulations, the baseline kinematics could not be reproduced with the reduced muscular capacity. Second, for 7 out of 12 cases where the baseline kinematics were achieved, this was possible with compensatory increased activation of some muscles with similar functions (p ≤ 0.003). Discussion: Evidently, due to the loss of the ankle plantar flexors, gait imposes a high demand on the flexor muscle group of the residual limb. This study highlights how the elevated cost of gait in this population manifests in muscle recruitment. To enhance functionality, it is critical to consider the mechanical demand on the hip flexors and to develop rehabilitation interventions accordingly.

Psychophysiological Adaptations to Yoga Practice in Overweight and Obese Individuals: A Topical Review

Physical activity has been documented as a foundational approach for weight management and obesity, improving several cardiometabolic and mental health indices. However, it is not clear whether yoga practice can induce beneficial improvements in anthropometric and body composition parameters, performance, metabolic health, and well-being among overweight/obese people. The aim of this topical review was to catalog training studies examining the psychophysiological responses to yoga interventions in order to detect which outcomes have been investigated, the research methods applied, and the conclusions. The inclusion/exclusion criteria were met by 22 published articles involving 1178 (56% female) overweight/obese participants. This brief review on yoga-induced adaptations demonstrates that this widely used meditative movement activity can meaningfully improve the vast majority of the selected markers. These beneficial alterations are focused mostly on various anthropometric and body composition variables, cardiovascular disease risk factors, physical fitness parameters, quality of life, and stress in previously inactive overweight/obese individuals. Instead, yoga-based physical exercise interventions investigating anxiety, depression, mood state, exercise enjoyment, affect valence, and adherence were limited. Further research should focus on the yoga intervention configuration and potential mechanisms behind favorable changes in various psychophysiological indices through large-scale, rigorously designed randomized controlled trials implementing long-term interventions in overweight/obese individuals.

Psychophysiological Adaptations to Pilates Training in Overweight and Obese Individuals: A Topical Review

The prevalence of overweightness and obesity has been documented as a major public health issue since it has increased at an alarming rate worldwide. Structured physical exercise programs have been reported as an essential strategy for preventing, managing, and treating obesity, inducing critical improvements in various physiological and psychological markers. However, it is unclear whether Pilates training can elicit positive changes in body composition, physical fitness, cardiometabolic health, and well-being among overweight and obese populations. The purpose of this topical review was to catalog studies investigating the physiological and psychological adaptations to Pilates training in order to identify what outcomes have been assessed, the research methods used, and the results. The inclusion/exclusion criteria were met by 14 published articles involving 582 participants (83% female) who were overweight or obese. The present topical review on Pilates training-induced adaptations shows that this widely used exercise type can significantly improve the majority of the selected indicators. These beneficial changes are frequently focused on anthropometric parameters, body composition, glucose, and lipid metabolism, as well as blood pressure in sedentary overweight or obese women. Specialized equipment-based Pilates interventions and trials investigating various mental health indices were limited. Further research is warranted in this area, emphasizing the Pilates training configuration and potential mechanisms behind positive alterations in several psychophysiological markers through large-scale randomized controlled trials with superior methodological quality, implementing long-term interventions in various populations that are overweight and obese.

The impact of the COVID-19 pandemic on perceptions of health, well-being, and college experience in Division III student-athletes

Objective: Determine the impact of the COVID-19 pandemic on student-athletes. Participants: Participants (n = 238) were Division III student-athletes (18-24yrs) enrolled at a Pennsylvania State University campus during the Fall 2020 semester. Methods: Student-athletes were emailed a link of a 43-question survey which was deployed using Qualtrics®. The survey asked questions about collegiate experience, health, well-being, sport related training, and physical fitness before and during the pandemic. Results: Approximately 94% of student-athletes reported that COVID-19 worsened their college experience. About 52 and 59% of student-athletes believed that COVID-19 had a negative impact on their health and well-being, respectively. Nearly 79% of student-athletes reported that their sport-related training decreased during the pandemic. Over half of participants believed that their physical fitness, endurance, and strength decreased during the pandemic. Conclusion: The implications of the COVID-19 pandemic on Division III collegiate student-athletes include a worsened college experience as well as worsened health and well-being.

Bored at home?—A systematic review on the effect of environmental enrichment on the welfare of laboratory rats and mice

Boredom is an emotional state that occurs when an individual has nothing to do, is not interested in the surrounding, and feels dreary and in a monotony. While this condition is usually defined for humans, it may very well describe the lives of many laboratory animals housed in small, barren cages. To make the cages less monotonous, environmental enrichment is often proposed. Although housing in a stimulating environment is still used predominantly as a luxury good and for treatment in preclinical research, enrichment is increasingly recognized to improve animal welfare. To gain insight into how stimulating environments influence the welfare of laboratory rodents, we conducted a systematic review of studies that analyzed the effect of enriched environment on behavioral parameters of animal well–being. Remarkably, a considerable number of these parameters can be associated with symptoms of boredom. Our findings show that a stimulating living environment is essential for the development of natural behavior and animal welfare of laboratory rats and mice alike, regardless of age and sex. Conversely, confinement and under-stimulation has potentially detrimental effects on the mental and physical health of laboratory rodents. We show that boredom in experimental animals is measurable and does not have to be accepted as inevitable.

Profiling the absolute and relative strength of a special operations police unit

Background

Specialist police perform high-risk tasks and are required to have, and maintain, a high level of fitness. The aims of this study were to profile the strength of a specialist police unit and to investigate whether this profile remained constant over an 18-month period.

Methods

Retrospective data for 47 special operations police officers (mean initial weight = 88.84 ± 8.25 kg) were provided. Officers were tested five times over 18 months for 1 repetition maximum: bench press, squat, deadlift, and pull-up. All officers continued to participate in their typical physical conditioning programs. Repeated-measures ANOVAs with Bonferroni post-hoc adjustments or Friedman tests with Wilcoxon signed-rank tests were used to compare strength values across all five time points (TPs). Alpha levels were set at 0.05.

Results

All strength values increased significantly over the 18-month period. Over the five TPs, absolute squat increased the most (+ 9%: initial mean = 125.79 ± 24.53 kg), followed by absolute bench press (+ 8%: initial mean = 109.67 ± 19.80 kg), absolute deadlift (+ 7%: initial mean = 151.64 ± 26.31 kg) and absolute pull-up (+ 4%: initial mean = 121.43 ± 14.91 kg). Relatively, the highest increase was found with the squat (+ 8%: initial mean = 1.42 ± 0.25%), followed by the bench press (+ 7%: initial mean = 1.24 ± 0.20%), deadlift (+ 6%: initial mean = 1.71 ± 0.25%) then pull-up (+ 4%: initial mean = 1.37 ± 0.15%). The period between TP3 and TP4 yielded the fewest significant increases compared with other TP differences with only absolute bench press (+ 1.7%), absolute squat (+ 1.1%) and relative bench press (+ 1.6%) changing significantly (p < 0.05).

Conclusions

Specialist police can maintain, even increase strength, while serving in specialist units if provided with a Strength and Conditioning coach and time to train. Given changes over time, constant monitoring is required and a single timepoint may not be optimal to establish normative data.

Association between health-related physical fitness and self-reported health status in older Taiwanese adults

Background

Aging is an inevitable process of life development. These physical changes may cause a decline in the functional adaptability and health of older adults. This study aims to determine if an association exists between health-related physical fitness measurements and self-reported health status in older Taiwanese adults.

Methods

A total of 22,389 Taiwanese adults aged 65 years or older were recruited as study participants. Demographic characteristics, life habits, anthropometric assessments, health-related physical fitness measurements, and self-reported health status from this dataset were analyzed using the chi-square test, one-way analysis of variance, and logistic regression analysis.

Results

The results showed that there was significant association between back scratch and self-reported health status (excellent/good) (odds ratio [OR], 1.003; 95% CI 1.000–1.006) after adjusting potential confounders (gender, height, weight, body mass index, education, monthly income, marital status, smoking status, and chewing betel nuts). However, adjusted OR for unhealthy status (poor/very poor) significantly decreased for chair sit-and-reach test (OR 0.994, 95% CI 0.988–0.999).

Conclusions

The present study reveals significant associations between health-related physical fitness measurements and self-reported health status in older Taiwanese adults. In particular, the waist-to-hip ratio could be involved in the cognitive process of one’s subjective health status, since individuals’ perception of their physical appearance affects their self-reported health. Future researches are suggested to investigate the causality between health-related physical fitness and subjective health status.

Sex differences and shifts in body composition, physical activity, and total energy expenditure across a 3-month expedition

OBJECTIVES

An energetically demanding environment like a wilderness expedition can lead to potent stressors on human physiology and homeostatic balance causing shifts in energy expenditure and body composition. These shifts likely have consequences on overall health and performance and may potentially differ by sex. It is therefore critical to understand the potential differential body composition and energy expenditure changes in response to a novel and challenging environment in both males and female bodies.

METHODS

Data were collected from 75 healthy individuals (female = 41; ages 18-53) throughout a 3-month long expedition in the American Rockies. Body mass, body fat, and lean muscle mass were measured before, during, and after the course. Physical activity intensity and energy expenditure were also measured in a subset of participants using the wGT3X-BT Actigraph wrist monitor and an accompanying Bluetooth heart rate monitor.

RESULTS

Over the 3-month period, individuals initially experienced declines in body mass, body fat percentage, and lean muscle mass. Participants partially rebounded from these deficits to maintain overall body mass with a slight recomposition of body fat and lean muscle mass. Our data also demonstrated that sex moderated total energy expenditure, where females experienced a modest decline whereas males experienced an increase in energy expenditure from the beginning to the end of the course.

CONCLUSIONS

Understanding changes in energy storage in the body and variation in energy expenditure between sexes during a 3-month expedition has critical implications for maintaining health and performance in an energetically demanding environment where resources may be scarce.

Usual and dual-task gait adaptations under visual stimulation in older adults at different ages

BACKGROUND

During the walk along the streets, older adults are exposed to various visual stimuli that can affect their gait in a harmful or beneficial way.

AIMS

To evaluate gait strategies during different situations with and without visual stimulation in older adults to identify the influence of the visual stimulus on these gait parameters.

METHODS

A total of 200 older adults were divided into 4 groups according to age range between 60 and 102 years. Gait was evaluated in the following situations: (1) habitual gait (HG); (2) gait with the visual stimulation (GVS) provided by a pedestrian traffic light, and (3) GVS associated with a cognitive task (GVS-C). The GAITRite Platinum equipment was used to assess gait variables.

RESULTS

Comparison of GVS and HG revealed that the visual stimulus influences the gait parameters and promotes a gait speed increase. However, to increase their gait speed, older adults aged 60-89 years used strategies of increased step length and cadence, whereas subjects older than 90 years used only strategies of increased cadence. In addition, comparison of GVS and GVS-C revealed a decrease in gait speed in all age ranges when the cognitive task was added, although this reduction was more pronounced in subjects older than 70 years.

CONCLUSION

Visual stimulus influences the gait parameters in older adults and the strategy used is different depending on their age, a fact that shows that traffic light may be an interesting strategy to improve the gait performance during physical therapy.

Sex Moderated Mediation of the Musculoskeletal Fitness in Relationship between High-Intensive Interval Training Performing during Physical Education Classes and Cardiorespiratory Fitness in Healthy Boys and Girls

High-intensive interval training (HIIT) is indicated as a means of improving cardiorespiratory fitness (CRF) and musculoskeletal fitness (MSF). The relationship between CRF and MSF was examined too. Little is known about gaining CRF from HIIT independence of MSF in adolescents. Therefore, this study is aimed at investigating whether MSF mediated the relationship between HIIT and CRF and whether sex moderate this relation. The study sample included 122 individuals (45 boys, 77 girls) 16.12 ± 0.38 years of secondary school age. Participants were assigned to the HIIT intervention or control groups. The intervention lasted 14 minutes during one physical education lesson per week for ten weeks. Outcome and potential mediator were residual changes calculated from pre- and postintervention results of MSF components: handgrip (HG), sit-ups (ABS), sit-and-reach (FL), vertical jump (VJ), and Harvard step-test representing cardiorespiratory fitness (CRF). MSF index (MSFI) was calculated as a construct, agglomerating all MSF, and tested its usefulness. HIIT significantly impacted CRF in boys and girls (B = 2.32, p = 0.032; B = 2.28, p = 0.005, respectively). The impact of the HIIT program on the ABS and FL was observed only in girls. The moderation effect of sex was confirmed. Significant effect of HIIT on CRF decreased (B_direct < B_total) and was no significant after including FL (B = 1.46, p = 0.62)—complete mediation, but no ABS (B = 2.97, p = 0.001)—partial mediation. CRF was mediated by changes in ABS (B = 2.28, p < 0.001) and FL (4.18, p < 0.001). MSFI was not mediating; its usefulness was limited. HIIT is an effective tool in the development of CRF in both sexes. MSF played a limited role in the relationship between HIIT and CRF. It suggested different mechanisms in both sexes: girls who performed better to the HIIT had better values of FL and ABS, but not boys. HIIT intervention involved modifications in ABS or FL, which also influenced the increase of CRF.

Fit to Play? Health-Related Fitness Levels of Youth Athletes: A Pilot Study

ABSTRACT

Pfeifer, CE, Sacko, RS, Ortaglia, A, Monsma, EV, Beattie, PF, Goins, J, and Stodden, DF. Fit to play? Health-related fitness levels of youth athletes: A pilot study. J Strength Cond Res 36(1): 245-251, 2022-A recent National Strength and Conditioning Association position statement suggests that many youth are not prepared for the physical demands of sport. The purpose of this study was to compare health-related fitness (HRF) of youth athletes with normative findings from the general population. We recruited 136 athletes (63 male and 73 female athletes) aged 11-19 (16.01 ± 1.35) years and collected HRF (body composition, cardiorespiratory endurance, musculoskeletal strength and endurance). Results were categorized based on FITNESSGRAM® standards and compared with Canadian youth general population normative data. Most male athletes were classified as "needs improvement" for cardiorespiratory and muscular endurance, and body mass index (BMI). Conversely, most female athletes were at or above the "healthy fitness zone" for all measures. Male athletes at both age groups (11-14, 15-19; p < 0.001) and female athletes aged 11-14 (p < 0.05) demonstrated lower cardiorespiratory endurance compared with Canadian general population. Female athletes (both age groups) demonstrated greater muscular strength, and male athletes (age, 15-19 years) demonstrated lower BMI than the Canadian general population. The results are concerning as male athletes demonstrated poorer HRF compared with the general population. Although most female athletes were within healthy ranges, a portion of them were still at risk. Considering the demands sport places on the body, evaluating HRF is paramount for performance and injury prevention but more importantly for overall health. Youth sport and strength coaches should evaluate and aim to enhance HRF, as participation in sport does not guarantee adequate HRF. Promoting long-term athletic development and life-long health should be a priority in youth.

Interrelation between physical activity and hamstring flexibility among university students

In recent time, the specialists in the field of physical education and health protection have no consensus on the need to include stretching exercises as an obligatory type of physical activity for apparently healthy young people. The problem is that most university students tend to have sedentary lifestyle. According to some reports, this can negatively affect the flexibility of the hamstrings and, as a result, lead to a decrease in physical performance. To maintain and develop flexibility, special stretching techniques are traditionally used, which caused the point about the necessity to include them in weekly physical activity. The opposite position is that flexibility is perfectly developed and maintained through the performance of healthier types of physical activity. In this case, the flexibility of the hamstrings should be correlated with the amount of physical activity. The aim of the research was to study the relationship between the amount of physical activity of students and the flexibility of the hamstrings. To achieve this aim, a correlation study was conducted. The results of the study showed that there is a noticeable significant correlation between the total value of physical activity of students and the flexibility of the hamstrings. This, in turn, is an additional reinforcement of the position that there is no strict need to include stretching as an obligatory component of the physical activity of university students to maintain and develop the flexibility of the hamstrings.

Effects of Attentional Focus on Muscular Endurance: A Meta-Analysis

Several studies explored the effects of attentional focus on resistance exercise, but their analysed outcomes most commonly involved surface electromyography variables. Therefore, the effects of attentional focus on resistance exercise performance remain unclear. The aim of this review was to perform a meta-analysis examining the acute effects of external focus vs. internal focus vs. control on muscular endurance. Five databases were searched to find relevant studies. The data were pooled in a random-effects meta-analysis. In the analysis for external vs. internal focus of attention, there were seven comparisons with 14 study groups. In the analyses for external focus vs. control and internal focus vs. control, there were six comparisons with 12 study groups. An external focus of attention enhanced muscular endurance when compared with an internal focus (Cohen's d: 0.58; 95% confidence interval (CI): 0.34 and 0.82) and control (Cohen's d: 0.42; 95% CI: 0.08 and 0.76). In the analysis for internal focus vs. control, there was no significant difference between the conditions (Cohen's d: -0.19; 95% CI: -0.45 and 0.07). Generally, these results remained consistent in the subgroup analyses for upper-body vs. lower-body exercises. From a practical perspective, the results presented in this review suggest that individuals should use an external focus of attention for acute enhancement of muscular endurance.

Low lysophosphatidylcholine induces skeletal muscle myopathy that is aggravated by high-fat diet feeding

Obesity alters skeletal muscle lipidome and promotes myopathy, but it is unknown whether aberrant muscle lipidome contributes to the reduction in skeletal muscle contractile force-generating capacity. Comprehensive lipidomic analyses of mouse skeletal muscle revealed a very strong positive correlation between the abundance of lysophosphatidylcholine (lyso-PC), a class of lipids that is known to be downregulated with obesity, with maximal tetanic force production. The level of lyso-PC is regulated primarily by lyso-PC acyltransferase 3 (LPCAT3), which acylates lyso-PC to form phosphatidylcholine. Tamoxifen-inducible skeletal muscle-specific overexpression of LPCAT3 (LPCAT3-MKI) was sufficient to reduce muscle lyso-PC content in both standard chow diet- and high-fat diet (HFD)-fed conditions. Strikingly, the assessment of skeletal muscle force-generating capacity ex vivo revealed that muscles from LPCAT3-MKI mice were weaker regardless of diet. Defects in force production were more apparent in HFD-fed condition, where tetanic force production was 40% lower in muscles from LPCAT3-MKI compared to that of control mice. These observations were partly explained by reductions in the cross-sectional area in type IIa and IIx fibers, and signs of muscle edema in the absence of fibrosis. Future studies will pursue the mechanism by which LPCAT3 may alter protein turnover to promote myopathy.

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.

Ergogenic Effects of Acute Caffeine Intake on Muscular Endurance and Muscular Strength in Women: A Meta-Analysis

This meta-analysis aimed to explore the effects of caffeine ingestion on muscular endurance and muscular strength in women. Five databases were searched to find relevant studies. A random-effects meta-analysis of standardized mean differences (SMD) was performed for data analysis. Subgroup meta-analyses explored the effects of caffeine on upper-body and lower-body muscular endurance and muscular strength. Eight crossover placebo-controlled studies were included in the review. In the main meta-analysis that considered data from all included studies, there was a significant ergogenic effect of caffeine on muscular endurance (SMD = 0.25; p = 0.027) and muscular strength (SMD = 0.18; p < 0.001). In a subgroup analysis that considered only upper-body exercises, there was a significant ergogenic effect of caffeine on muscular endurance (SMD = 0.20; p = 0.007) and muscular strength (SMD = 0.17; p < 0.001). In a subgroup analysis that considered only lower-body exercises, there was no significant difference between caffeine and placebo for muscular endurance (SMD = 0.43; p = 0.092) or muscular strength (SMD = 0.16; p = 0.109). The main finding of this meta-analysis is that caffeine ingestion has a significant ergogenic effect on muscular endurance and muscular strength in women. The effects reported in this analysis are similar to those previously observed in men and suggest that women may use caffeine supplementation as an ergogenic aid for muscular performance. Future research is needed to explore the effects of caffeine on lower-body muscular endurance and muscular strength in this population.

Relationship between muscular fitness and bone health in young baseball players

The physical actions developed by baseball players can increase muscular fitness, and consequently improve bone health. The objective was to relate some indicators of muscular fitness to bone health in young baseball players. A descriptive cross-sectional study was carried out in 102 children and adolescent baseball players of the Brazilian National Team. The age range ranged from 9.0 to 15.0 years, the average chronological age was 12.2±2.2 years and the maturity status was 14.8±0.5 APHV (age at peak height velocity). Anthropometry, body composition [% fat, fat mass (FM) and fat-free mass (FFM)], physical tests [horizontal jump (HJ) and medicine ball throw (MBT)] bone health was estimated by anthropometry [bone mineral density (BMD) and bone mineral content (BMC)]. There was positive and significant correlation between bone health with FFM (r2= 89%) and with muscle strength tests (HJ and MBT) (R2= 55 to 75%). Young baseball players classified with low bone health level, reflected decreased values of FFM, HJ and MBT, in relation to young players classified with moderate and high bone health level (p<0.05). It was shown that good bone health is a consequence of a greater presence of muscular fitness, as a result of increased physical activity. These results suggest that emphasis should be placed on those young people who present a greater risk of having low BMD and BMC.

Concurrent Validity and Reliability of a Novel Visual Analogue Fitness Perception Scale for Adolescents (FP VAS A)

Introduction: Self-reported physical fitness (PF) provides an accurate measure of PF, specifically for young people. The Visual Analogue Scale (VAS) is one of the most used psychosocial measurement methods. The main arguments in favor of VAS are its ease of use and comprehension, particularly for less educated participants. There are some scales that assess self-perception of PF, but the VAS presented in this study covers a higher range of responses and a number of variables than other already validated measures. Aims: The aim was to determine the concurrent validity of the Visual Analogue Fitness Perception Scale for Adolescents (FP VAS A) (Sub-study 1) and check its reliability (Sub-study 2). Methods: Anthropometric and body composition measurements were performed, as well as PF tests (manual dynamometry, Course Navette, 4 × 10 m, and sit and reach). The International Fitness Scale (IFIS) and FP VAS A were used to assess self-reported PF. Results: Two sub-studies were carried out: in sub-study 1 a total of 67 students (26 males and 41 females aged 12–16 years) participated. The results showed a significant direct correlation between the level of PF and self-perception of PF (IFIS and FP VAS A), with the FP VAS A obtaining a higher correlation with PF (r = 0.444 to 0.666) than the IFIS and PF (r = 0.154 to 0.557). In sub-study 2 (test–retest of the FP VAS A), a total of 217 students (120 males and 97 females aged 12–17 years) participated. It showed a moderate reliability for all items; the intraclass correlation coefficient (ICC) was between 0.800 and 0.870, and kappa values ranged from 0.622 (endurance) to 0.458 (flexibility). In addition, Cronbach’s α for the total was 0.860. Conclusion: This study showed good validity and reliability for the FP VAS A in adolescents.

Ten-year resistance training background modulates somatosensory P3 cognitive brain resonse in older men: A magnetoencephalograpy study

The brain electrophysiological component P3, associated with good cognitive abilities, deteriorates during healthy aging. Both cognitive functions and P3 component amplitude respond positively to exercise, but the effects of resistance training on P3 are much less studied. Short-term resistance training interventions in older adults indicate modulation towards larger P3 amplitude, but this association has not been studied with a longitudinal study design. We investigated magnetoencephalographically recorded P3 (P3m) in a unique study design of nine aged men (mean age 77.7 y) with quasi-supervised resistance training background over a 10-year period and eight controls of similar age (mean age 77.5 y) with no training background. We elicited P3m utilizing lower limb electrical stimulation, as the resistance training program was mostly directed to lower limbs. Somatosensory oddball paradigm was performed with the right foot's fourth toe as standard (90%) and hallux as deviant (10%). Participants were asked to respond to deviants with a button press using their left index finger. Topographic maps showed bilateral temporoparietal activation for P3m in both groups. No amplitude differences were found in active P3m regions between groups. However, the groups differed in hemispheric activity of P3m. The exercise group showed stronger activation in the right frontotemporal and parietal sensor-groups compared to the left sensor-groups, and the control group showed stronger activation in right frontotemporal sensor-group compared to left. The control group showed shorter P3m latency in the right temporal sensor-group than the exercise group, but the latencies in other sensor-groups were similar. In aging, the brain utilizes compensatory areas to perform cognitive tasks. Our results suggest modulation in topographic distribution of P3m activity in aging men with long-term resistance training background compared to their controls. This might arise from a difference in age-related compensatory mechanisms in P3m generation.

Hybrid neuromuscular training promotes musculoskeletal adaptations in inactive overweight and obese women: A training-detraining randomized controlled trial

This study investigated the effects of a 10-month high-intensity interval-type neuromuscular training programme on musculoskeletal fitness in overweight and obese women. Forty-nine inactive females (36.4 ± 4.4 yrs) were randomly assigned to either a control (N = 21), a training (N = 14, 10 months) or a training-detraining group (N = 14, 5 months training followed by 5 months detraining). Training used progressive loaded fundamental movement patterns with prescribed work-to-rest intervals (1:2, 1:1, 2:1) in a circuit fashion (2-3 rounds). Muscular strength and endurance, flexibility, passive range of motion (PRoM), static balance, functional movement screen (FMS) and bone mass density (BMD) and content (BMC) were measured at pre-, mid-, and post-intervention. Ten months of training induced greater changes than the controls in (i) BMD (+1.9%, p < 0.001) and BMC (+1.5%, p = 0.023) ii) muscular strength (25%-53%, p = 0.001-0.005); iii) muscular endurance (103%-195%, p < 0.001); and iv) mobility (flexibility: 40%, p < 0.001; PRoM [24%-53%, p = 0.001-0.05;]; balance: 175%, p = 0.058; FMS: +58%, p < 0.001). The response rate to training was exceptionally high (86-100%). Five months of detraining reduced but not abolished training-induced adaptations. These results suggest that a hybrid-type exercise approach integrating endurance-based bodyweight drills with resistance-based alternative modes into a real-world gym setting may promote musculoskeletal fitness in overweight and obese women.

Physical activity and exercise: Strategies to manage frailty

Frailty, a consequence of the interaction of the aging process and certain chronic diseases, compromises functional outcomes in the elderly and substantially increases their risk for developing disabilities and other adverse outcomes. Frailty follows from the combination of several impaired physiological mechanisms affecting multiple organs and systems. And, though frailty and sarcopenia are related, they are two different conditions. Thus, strategies to preserve or improve functional status should consider systemic function in addition to muscle conditioning. Physical activity/exercise is considered one of the main strategies to counteract frailty-related physical impairment in the elderly. Exercise reduces age-related oxidative damage and chronic inflammation, increases autophagy, and improves mitochondrial function, myokine profile, insulin-like growth factor-1 (IGF-1) signaling pathway, and insulin sensitivity. Exercise interventions target resistance (strength and power), aerobic, balance, and flexibility work. Each type improves different aspects of physical functioning, though they could be combined according to need and prescribed as a multicomponent intervention. Therefore, exercise intervention programs should be prescribed based on an individual's physical functioning and adapted to the ensuing response.

Effects of Dietary Nitrate Supplementation on Weightlifting Exercise Performance in Healthy Adults: A Systematic Review

Dietary nitrate (NO3-) supplementation has been evidenced to induce an ergogenic effect in endurance and sprint-type exercise, which may be underpinned by enhanced muscle contractility and perfusion, particularly in type II muscle fibers. However, limited data are available to evaluate the ergogenic potential of NO3- supplementation during other exercise modalities that mandate type II fiber recruitment, such as weightlifting exercise (i.e., resistance exercise). In this systematic review, we examine the existing evidence basis for NO3- supplementation to improve muscular power, velocity of contraction, and muscular endurance during weightlifting exercise in healthy adults. We also discuss the potential mechanistic bases for any positive effects of NO3- supplementation on resistance exercise performance. Dialnet, Directory of Open Access Journals, Medline, Pubmed, Scielo, Scopus and SPORT Discus databases were searched for articles using the keywords: nitrate or beetroot and supplement or nut*r or diet and strength or "resistance exercise" or "resistance training" or "muscular power". Four articles fulfilling the inclusion criteria were identified. Two of the four studies indicated that NO3- supplementation could increase aspects of upper body weightlifting exercise (i.e., bench press) performance (increases in mean power/velocity of contraction/number of repetitions to failure), whereas another study observed an increase in the number of repetitions to failure during lower limb weightlifting exercise (i.e., back squat). Although these preliminary observations are encouraging, further research is required for the ergogenic potential of NO3- supplementation on weightlifting exercise performance to be determined.

Physiological Predictors of Performance on the CrossFit "Murph" Challenge

We examined physiological predictors of performance on the CrossFit Murph challenge (1-mile run, 100 pullups, 200 pushups, 300 air squats, 1-mile run). Male CrossFit athletes (n = 11, 27 ± 3 years) performed a battery of physical assessments including: (1) body composition, (2) upper and lower body strength, (3) upper body endurance, (4) anaerobic power, and (5) maximal oxygen consumption. No less than 72 h later, participants completed the Murph challenge, heart rate was monitored throughout, and blood lactate was obtained pre-post. Correlations between physiological parameters and total Murph time, and Murph subcomponents, were assessed using Pearson's correlations. Murph completion time was 43.43 ± 4.63 min, and maximum and average heart rate values were 185.63 ± 7.64 bpm and 168.81 ± 6.41 bpm, respectively, and post-Murph blood lactate was 10.01 ± 3.04 mmol/L. Body fat percentage was the only physiological parameter significantly related to total Murph time (r = 0.718; p = 0.013). Total lift time (25.49 ± 3.65 min) was more strongly related (r = 0.88) to Murph time than total run time (17.60 ± 1.97 min; r = 0.65). Greater relative anaerobic power (r = -0.634) and less anaerobic fatigue (r = 0.649) were related to total run time (p < 0.05). Individuals wanting to enhance overall Murph performance are advised to focus on minimizing body fat percentage and improving lift performance. Meanwhile, performance on the run subcomponent may be optimized through improvements in anaerobic power.

The Influence of Caffeine Supplementation on Resistance Exercise: A Review

This paper aims to critically evaluate and thoroughly discuss the evidence on the topic of caffeine supplementation when performing resistance exercise, as well as provide practical guidelines for the ingestion of caffeine prior to resistance exercise. Based on the current evidence, it seems that caffeine increases both maximal strength and muscular endurance. Furthermore, power appears to be enhanced with caffeine supplementation, although this effect might, to a certain extent, be caffeine dose- and external load-dependent. A reduction in rating of perceived exertion (RPE) might contribute to the performance-enhancing effects of caffeine supplementation as some studies have observed decreases in RPE coupled with increases in performance following caffeine ingestion. However, the same does not seem to be the case for pain perception as there is evidence showing acute increases in resistance exercise performance without any significant effects of caffeine ingestion on pain perception. Some studies have reported that caffeine ingestion did not affect exercise-induced muscle damage, but that it might reduce perceived resistance exercise-induced delayed-onset muscle soreness; however, this needs to be explored further. There is some evidence that caffeine ingestion, compared with a placebo, may lead to greater increases in the production of testosterone and cortisol following resistance exercise. However, given that the acute changes in hormone levels seem to be weakly correlated with hallmark adaptations to resistance exercise, such as hypertrophy and increased muscular strength, these findings are likely of questionable practical significance. Although not without contrasting findings, the available evidence suggests that caffeine ingestion can lead to acute increases in blood pressure (primarily systolic), and thus caution is needed regarding caffeine supplementation among individuals with high blood pressure. In the vast majority of studies, caffeine was administered in capsule or powder forms, and therefore the effects of alternative forms of caffeine, such as chewing gums or mouth rinses, on resistance exercise performance remain unclear. The emerging evidence suggests that coffee might be at least equally ergogenic as caffeine alone when the caffeine dose is matched. Doses in the range of 3-9 mg·kg^-1 seem to be adequate for eliciting an ergogenic effect when administered 60 min pre-exercise. In general, caffeine seems to be safe when taken in the recommended doses. However, at doses as high as 9 mg·kg^-1 or higher, side effects such as insomnia might be more pronounced. It remains unclear whether habituation reduces the ergogenic benefits of caffeine on resistance exercise as no evidence exists for this type of exercise. Caution is needed when extrapolating these conclusions to females as the vast majority of studies involved only male participants.

BIA-assessed cellular hydration and muscle performance in youth, adults, and older adults

BACKGROUND & AIMS

Alterations in body hydration can have an impact on muscle performance, with consequences not only at a sporting level, but on overall health and daily functional competence. Given that the estimation of body water from BIA is based on prediction equations involving assumptions on tissue hydration and body geometry, it is unclear if phase angle (PhA), which is not influenced by assumptions, is a better marker of muscle performance than the BIA estimated parameters of body water. Therefore, the aims of this investigation were to analyze the relationships of BIA-estimated body water compartments with muscle performance among youth, adults, and older adults, and to assess the added value of PhA as a marker of muscle performance.

METHODS

BIA assessments were completed on 263 youth (ages 6-17), 249 adults (ages 18-64), and 75 older adults (ages 65+). Muscle performance was assessed by jumping mechanography (power and force) and handgrip strength. Partial correlations were used to compare the degree of association among the BIA measures with muscle performance for each age group, controlling for sex, age, and body weight.

RESULTS

TBW, ICW, and PhA were associated with muscle performance at the lower and upper limbs in all age groups (p < 0.05), with the exception of PhA with handgrip strength in adults and older adults and TBW with lower limb total force in the older adults. In youth, the highest associations observed were PhA with lower limb muscle power (r = 0.45, CI:0.35-0.54, p < 0.05) and with handgrip strength (r = 0.42, CI:0.32-0.52, p < 0.05). In adults and older adults, the major associations observed were those of ICW with lower limb muscle power (adults, r = 0.53, CI:0.43-0.61, p < 0.05; older adults, r = 0.52, CI = 0.33-0.67, p < 0.05). ECW had significantly lower associations (p < 0.05) with both lower limb force and power in adults and older adults compared to youth. In the older adults, ECW was negatively associated with lower limb total force (r = -0.24; p < 0.05).

CONCLUSIONS

BIA derived hydration parameters may be useful markers of muscle performance in all age groups. In particular, the ICW compartment was a better predictor of muscle performance in adults and older adults compared to youth. In youth, PhA had stronger associations with muscle performance than those of ICW. Thus, phase angle appears to be a useful marker of muscle performance, particularly in youth.