Sex differences in neuromuscular and biological determinants of isometric maximal force

AIM

Force expression is characterized by an interplay of biological and molecular determinants that are expected to differentiate males and females in terms of maximal performance. These include muscle characteristics (muscle size, fiber type, contractility), neuromuscular regulation (central and peripheral factors of force expression), and individual genetic factors (miRNAs and gene/protein expression). This research aims to comprehensively assess these physiological variables and their role as determinants of maximal force difference between sexes.

METHODS

Experimental evaluations include neuromuscular components of isometric contraction, intrinsic muscle characteristics (proteins and fiber type), and some biomarkers associated with muscle function (circulating miRNAs and gut microbiome) in 12 young and healthy males and 12 females.

RESULTS

Male strength superiority appears to stem primarily from muscle size while muscle fiber-type distribution plays a crucial role in contractile properties. Moderate-to-strong pooled correlations between these muscle parameters were established with specific circulating miRNAs, as well as muscle and plasma proteins.

CONCLUSION

Muscle size is crucial in explaining the differences in maximal voluntary isometric force generation between males and females with similar fiber type distribution. Potential physiological mechanisms are seen from associations between maximal force, skeletal muscle contractile properties, and biological markers.

Randomised controlled trial combining vitamin E-functionalised chocolate with physical exercise to reduce the risk of protein-energy malnutrition in predementia aged people: study protocol for Choko-Age

OBJECTIVE

Protein-energy malnutrition and the subsequent muscle wasting (sarcopenia) are common ageing complications. It is knowing to be also associated with dementia. Our programme will test the cytoprotective functions of vitamin E combined with the cortisol-lowering effect of chocolate polyphenols (PP), in combination with muscle anabolic effect of adequate dietary protein intake and physical exercise to prevent the age-dependent decline of muscle mass and its key underpinning mechanisms including mitochondrial function, and nutrient metabolism in muscle in the elderly.

METHODS AND ANALYSIS

In 2020, a 6-month double-blind randomised controlled trial in 75 predementia older people was launched to prevent muscle mass loss, in respond to the 'Joint Programming Initiative A healthy diet for a healthy life'. In the run-in phase, participants will be stabilised on a protein-rich diet (0.9-1.0 g protein/kg ideal body weight/day) and physical exercise programme (high-intensity interval training specifically developed for these subjects). Subsequently, they will be randomised into three groups (1:1:1). The study arms will have a similar isocaloric diet and follow a similar physical exercise programme. Control group (n=25) will maintain the baseline diet; intervention groups will consume either 30 g/day of dark chocolate containing 500 mg total PP (corresponding to 60 mg epicatechin) and 100 mg vitamin E (as RRR-alpha-tocopherol) (n=25); or the high polyphenol chocolate without additional vitamin E (n=25). Muscle mass will be the primary endpoint. Other outcomes are neurocognitive status and previously identified biomolecular indices of frailty in predementia patients. Muscle biopsies will be collected to assess myocyte contraction and mitochondrial metabolism. Blood and plasma samples will be analysed for laboratory endpoints including nutrition metabolism and omics.

ETHICS AND DISSEMINATION

All the ethical and regulatory approvals have been obtained by the ethical committees of the Azienda Ospedaliera Universitaria Integrata of Verona with respect to scientific content and compliance with applicable research and human subjects' regulation. Given the broader interest of the society toward undernutrition in the elderly, we identify four main target audiences for our research activity: national and local health systems, both internal and external to the project; targeted population (the elderly); general public; and academia. These activities include scientific workshops, public health awareness campaigns, project dedicated website and publication is scientific peer-review journals.

TRIAL REGISTRATION NUMBER

NCT05343611.

Evaluating field-goal shooting effectiveness in wheelchair basketball players across a competitive season: a preliminary study

Background

Information about non-elite wheelchair basketball (WB) players across national competitive seasons are still missing. This study aimed at identifying which situational-related variables were associated with shooting effectiveness in non-elite WB players.

Methods

All the matches played by one WB team across one national competitive season were video-recorded and analysed; 333 shooting attempts from high-point players and several situational-related variables were considered.

Results

Pearson's Chi-square test showed that increased shooting effectiveness under the following conditions: playing on home ground, during won matches, while taking shots with the wheelchair in motion, and when no opposing player raised their arm in defence. Results of the multivariable logistic regression analysis showed a statistically significant influence of match location (p-value = 0.001), shot-clock remaining (p-value = 0.015) and modality of press (p-value < 0.001). The highest attack effectiveness was achieved when teams played at home (odds ratio [OR] = 2.49), while the shooting effectiveness decreased when the shot occurred during the last seconds of the action (OR = 0.36), or the opponents defended with the arm raised (OR = 0.19). These results suggest that coaches should include exercises aimed at shooting under conditions of increased pressure in their programmes in order to create specific situations during the training sessions to prepare their high-point athletes for shots under specific match constraints.

Predictors of Ball Velocity in the Sitting Volleyball Serve: A Causal Analysis

This study explored the performance of the Sitting Volleyball serve by investigating the causal factors associated with ball velocity. Thirty-seven athletes underwent anthropometry and strength assessment and performed ten successful maximal effort serves. Ball velocity was measured using a sports radar gun. The hip, shoulder, elbow and wrist angles at the instant of ball impact as well as the height of ball impact were estimated through two-dimensional motion analysis. The causal relationships between variables were described through a linear Structural Equation Model and a Directed Acyclic Graph. Results showed that a smaller hip angle determines a greater shoulder angle, which in turn causes a greater elbow angle. A more open elbow angle together with a greater vertical reach allowed for a greater height of ball impact. Finally, increased height of ball impact along with greater abdominal strength are beneficial for higher ball velocity. These results underlined that the Sitting Volleyball serve is a multifactorial stroke involving anthropometric, technical and strength factors and suggest that athletes should improve their abdominal strength and master the technique necessary to perform the serve with the shoulder and the elbow joints fully extended in order to produce the greatest possible impact on the ball.

Anthropometric prediction of DXA-measured percentage of fat mass in male karate athletes

BACKGROUND

In karate, high percentages of fat mass (%FM) are often associated with poor sport performance. Dual-energy X-ray absorptiometry (DXA) can accurately measure the %FM (%FM-DXA), but it may not be practical in some sport settings, where anthropometry has long been used as an alternative. This study aimed to explore the ability of sixteen available anthropometric equations to estimate the %FM (%FM-AE) in karate athletes using the %FM-DXA as the criterion. Furthermore, two population-specific predictive equations to estimate the %FM-DXA were developed from anthropometric measurements.

METHODS

Forty-six male athletes aged 21.7±3.8 years underwent anthropometry and a whole-body DXA scan.

RESULTS

The results showed that in male karate athletes all the considered anthropometric equations are mostly inaccurate in estimating the %FM-DXA within a range of the limits of agreement in the Bland-Altman analysis, which ranged from 6.43% to 13.37%. Regression analysis yielded two statistically significant models (P<0.001 for both) to predict the %FM-DXA. In the first model (cross-validated estimation of R²=0.85), the predictors were the abdominal, triceps, calf, and biceps skinfolds and in the second model (cross-validated estimation of R²=0.77), the predictor was the sum of nine skinfolds (i.e., biceps, triceps, subscapular, chest, axilla, suprailiac, abdominal, anterior thigh and calf skinfolds).

CONCLUSIONS

These results underlined the need for sport-specific anthropometric equations to accurately estimate the %FM-DXA in male karate athletes. The two predictive anthropometric equations presented in this study provided a promising tool for professionals dealing with body composition in this athletic population to accurately estimate the %FM-DXA by means of anthropometry.

The role of muscle mass in vascular remodeling: insights from a single-leg amputee model

PURPOSE

Both muscle mass and physical activity are independent mechanisms that play a role in vascular remodeling, however, the direct impact of muscle mass on the structure and function of the vessels is not clear. The aim of the study was to determine the impact of muscle mass alteration on lower limbs arterial diameter, blood flow, shear rate and arterial stiffness.

METHODS

Nine (33 ± 13 yrs) male individuals with a single-leg amputation were recruited. Vascular size (femoral artery diameter), hemodynamics (femoral artery blood flow and shear rate were measured at the level of the common femoral artery in both amputated (AL) and whole limbs (WL). Muscle mass of both limbs, including thigh for AL and thigh and leg for WL, was measured with a DXA system.

RESULTS

AL muscle mass was reduced compared to the WL (3.2 ± 1.2 kg vs. 9.4 ± 2.1 kg; p = 0.001). Diameter of the femoral artery was reduced in the AL (0.5 ± 0.1 cm) in comparison to the WL (0.9 ± 0.2 cm, p = 0.001). However, femoral artery blood flow normalized for the muscle mass (AL = 81.5 ± 78.7ml min^-1 kg^-1,WL = 32.4 ± 18.3; p = 0.11), and blood shear rate (AL = 709.9 ± 371.4 s^-1, WL = 526,9 ± 295,6; p = 0.374) were non different between limbs. A correlation was found only between muscle mass and femoral artery diameter (p = 0.003, R = 0.6561).

CONCLUSION

The results of this study revealed that the massive muscle mass reduction caused by a leg amputation, but independent from the level of physical activity, is coupled by a dramatic arterial diameter decrease. Interestingly, hemodynamics and arterial stiffness do not seem to be impacted by these structural changes.

Sporting activity does not fully prevent bone demineralization at the impaired hip in athletes with amputation

There is lack of information about bone mineralization at the lumbar spine and bilateral hips of athletes with unilateral lower limb amputation. The present study assessed for the first time the areal bone mineral density at the lumbar spine and at the hip of the able and impaired leg by means of Dual-Energy X-Ray Absorptiometry using a large sample (N = 40) of male athletes. Results showed that bone demineralization in athletes with unilateral lower limb amputation is found at the impaired hip but not at the lumbar spine and may therefore be site-specific. The extent of hip demineralization was influenced by the level of amputation, with about 80% of athletes with above knee amputation and 10% of athletes with below knee amputation showing areal bone mineral density below the expected range for age. Nevertheless, a reduced percentage of fat mass and a lower fat-to-lean mass ratio in the residual impaired leg as well as a greater amount of weekly training was positively associated with bone mineralization at the impaired hip (partial correlation coefficients = 0.377–0.525, p = 0.040–0.003). Results showed that participation in adapted sport has a positive effect on bone health in athletes with unilateral lower limb amputation but is not sufficient to maintain adequate levels of bone mineralization at the impaired hip in athletes with above-knee amputation. Accordingly, physical conditioners should consider implementing sporting programs, according to the severity of the impairment, aimed at improving bone mineralization at the impaired hip and improve body composition in the residual impaired leg.

Physique and performance in male sitting volleyball players: implications for classification and training

Background

This study assessed whether anthropometry, physical fitness and sport-specific sprint performance vary across the three groups of sitting volleyball (SV) athletes (athletes with a disability (VS1), athletes with a minimal disability (VS2) and able-bodied SV athletes (AB)) in order to explore the validity of the current system of classification. This study also investigated how the anthropometric and physical fitness characteristics of athletes relate to their sprint performance.

Methods

Thirty-five SV male athletes aged 37.4 ± 10.8 years and practicing SV at a national/international level volunteered for this study. Testing consisted in the evaluation of linear anthropometry, physical fitness (body composition by-means of dual-energy X-ray absorptiometry and upper-body strength) and sprint performance (5-meter sprint tests, agility test and speed and endurance test).

Results

Athletes in the three groups differed in fat mass percentage (%FM) which was higher in VS1 versus AB at the sub-total level (+9%), in the arms (+15%) and in the non-impaired leg (+8%) regions. Greater hand span, greater length of the impaired lower leg, lower %FM at both the sub-total and regional level and a higher level of strength in the upper body are all associated with better performances in the considered sprint tests (P < 0.05 for all). These results do not confirm the validity of the current system of classification of athletes adopted in SV. Professionals dealing with SV athletes should include specific exercises aimed at improving whole-body and regional body composition and the strength of the trunk and upper limbs in their training programs.

Is handgrip strength a marker of muscle and physical function of the lower limbs? Sex differences in older adults with obesity

BACKGROUND AND AIMS

In this cross-sectional study we investigate the association between handgrip strength (HGS) and muscle function of the lower limbs and the predictors of the appendicular lean mass index (ALMI) in older adults with obesity of both sexes.

METHODS AND RESULTS

Eighty-four older (67 ± 5 years) men (N = 44) and women (N = 40) with obesity (body mass index (BMI) 33 ± 4 kg/m²) performed: the HGS, isokinetic knee extensors (KE) and flexors (KF) muscle strength and power and Short Physical Performance Battery (SPPB). The correlation between HGS and lower limbs muscle function was evaluated, and four multiple hierarchical linear models were built to assess the contribution of each ALMI predictor (i.e., HGS, BMI, SPPB, muscle strength and power). In men, HGS was weakly-to-moderately associated (p < 0.05) with KE, KF muscle function and physical performance. In women, HGS showed a weak association (p < 0.05) with KE muscle function. The significant predictors of ALMI were only the BMI in women, whereas in the group of men BMI, KE maximal strength and power better explain the variance in ALMI than HGS alone.

CONCLUSION

Our results suggest that HGS should not be used alone as a marker of lower muscle nor physical function. Sex differences exist with the BMI that is a contributor of ALMI both in men and women. However, at least in the group of men, markers related to strength and power of the lower limbs can better describe variations in ALMI compared to HGS in this kind of population.

CLINICAL TRIAL REGISTRATION

NA.

Relationships between anthropometric characteristics, block settings, and block clearance technique during the sprint start

This study aimed to identify how body dimensions interact with anteroposterior block distances to influence lower limb joint angles in the "set" position, how these angles relate to block clearance kinetic and kinematic parameters, and how these biomechanical parameters influence sprint start performance in sprinters of both sexes and of different ability levels. Seventy-eight sprinters performed six maximal-effort 10 m sprints. Joint angles in the "set" position were quantified through 2D video analysis, and the forces generated during block exit were measured by dynamometric starting blocks. Lower limb length was associated with the front block-starting line distance ([FB/SL], partial correlation [r_PC] = 0.48) and was a significant predictor of FB/SL (R² = 0.39). The FB/SL was associated with front hip angle (r_PC = 0.38), which was consequently associated with numerous kinetic variables during block clearance (r_PC from -0.41 to -0.61). Coaches should be encouraged to explore the interactions between individual lower limb lengths and the FB/SL distance in both male and female sprinters to manipulate the front hip angle in the "set" position in an attempt to achieve more favourable block clearance kinetics.

Body composition and bone mineral density in athletes with a physical impairment

Background

The impact of the type and the severity of disability on whole-body and regional body composition (BC), and bone mineral density (BMD) must be considered for dietary advice in athletes with a physical impairment (PI). This study aimed to investigate the impact of the type and the severity of disability on BC, the pattern of distribution of fat mass at the regional level, and BMD in athletes with a PI.

Methods

Forty-two male athletes with spinal cord injury (SCI, n = 24; age = 40.04 ± 9.95 years, Body Mass Index [BMI] = 23.07 ± 4.01 kg/m²) or unilateral lower limb amputation (AMP, n = 18; age = 34.39 ± 9.19 years, BMI = 22.81 ± 2.63 kg/m²) underwent a Dual-Energy X-Ray Absorptiometry scan. Each athlete with a PI was matched by age with an able-bodied athlete (AB, n = 42; age = 37.81 ± 10.31 years, BMI = 23.94 ± 1.8 kg/m²).

Results

One-Way Analysis of Variance showed significant differences between the SCI, AMP and AB groups for percentage fat mass (%FM) (P < 0.001, eta squared = 0.440). Post-hoc analysis with Bonferroni’s correction showed that athletes with SCI had significantly higher %FM vs. the AMP and AB groups (25.45 ± 5.99%, 21.45 ± 4.21% and 16.69 ± 2.56%, respectively; P = 0.008 vs. AMP and P < 0.001 vs. AB). The %FM was also significantly higher in the AMP vs. the AB group (P < 0.001). Whole-body BMD was negatively affected in SCI athletes, with about half of them showing osteopenia or osteoporosis. In fact, the mean BMD and T-score values in the SCI group (1.07 ± 0.09 g/cm² and −1.25 ± 0.85, respectively) were significantly lower in comparison with the AB group (P = 0.001 for both) as well as the AMP group (P = 0.008 for both). The type of disability affected BC and BMD in the trunk, android, gynoid and leg regions in SCI athletes and the impaired leg only in AMP athletes.

Conclusions

In conclusion, the type of disability and, partly, the severity of PI impact on BC and BMD in athletes with a PI. Nutritionists, sports medicine doctors, clinicians, coaches and physical conditioners should consider athletes with SCI or AMP separately. Athletes with a PI would benefit from specific nutrition and training programs taking into account the type of their disability.

Long-Term Patterns of Bone Mineral Density in an Elite Soccer Player

Changes in bone mineral density (BMD) have been associated with association football (soccer) participation. Seasonal changes in BMD of soccer players have been proposed as well. However, previous investigations were based on short-term observations. Actually, longitudinal investigation of BMD in soccer players is lacking, possibly because of frequent inter-club transfer, changes in club policy or continued availability of the relevant facilities. Dual-energy X-ray Absorptiometry (DXA)-measured areal BMD (aBMD) was obtained during the competitive season in an elite soccer player along 10 consecutive years. Findings showed that (1) aBMD tends to increase with age, independently of body mass; (2) The right (preferred, kicking) leg has higher aBMD than the left (non-preferred, support) one; (3) Meaningful (i.e., >least significant change, LSC) changes in aBMD take place along the season; and (4) The off-season (transition) period has no effect on aBMD. Findings prompt for future research aimed at clarifying the long-term and seasonal patterns of bone characteristics in soccer in relation with age and type/dose of training. Season-around, long-term scrutiny of bone status in soccer players would help controlling for possible changes/asymmetries in bone mineralization/strength.

Dietary Intakes and Food Habits of Wheelchair Basketball Athletes compared to Gym Attendees and Individuals who do not Practice Sport Activity

BACKGROUND

Mediterranean diet (Med-D) has been previously suggested for athletes, but Paralympics usually have a low intake of plant foods. Orthorexia nervosa (ON) can drive dietary intake of both athletes and gym attendees.

OBJECTIVE

We aimed to compare dietary intakes and food habits of elite wheelchair basketball athletes (WBA) and able-bodied individuals who practice or not sport activity and with different fat mass percentage (FM%).

METHODS

We recruited 15 WBA from the Italian National team and 3 control groups (15 each group): healthy individuals who do not practice any sport activity (NSA) and gym attendees with low (GAL, FM%<17) and high (GAH, FM%>18) FM%. Food consumption was monitored by 3-d diary, while Med-D scores and ON score were evaluated through standardized questionnaires. In WBA we also assessed Neurogenic Bowel Dysfunction (NBD), GastroEsophageal Reflux Disease (GERD), allergy questionnaire for athletes (AQUA) and Starvation Symptoms Inventory (SSI).

RESULTS

In WBA, ON correlated with GERD and SSI. WBA and GAH with eating behavior of ON had higher adherence to Med-D, whereas NSA had less adherence to Med-D. Sub-score including fruits, vegetables and legumes, was higher in the GAL and GAH groups compared to the WBA and NSA groups. Med-D was inversely related to animal protein intake (PRO-AN) in NSA and GAL. FM% was inversely related to PRO-AN in WBA and GAH, and to ON only in GAH. In WBA PRO-AN and vegetable protein intake correlated with both carbohydrate and energy intakes.

CONCLUSIONS

In WBA, commitment to wellness (ON and Med-D adherence) could be a response to gastrointestinal and starvation symptoms. WBA should be involved in setting their own individualized dietary strategies.

Full characterisation of knee extensors' function in ageing: effect of sex and obesity

BACKGROUND/OBJECTIVES

Muscle function is a marker of current and prospective health/independence throughout life. The effects of sex and obesity (OB) on the loss of muscle function in ageing remain unresolved, with important implications for the diagnosis/monitoring of sarcopenia. To characterise in vivo knee extensors' function, we compared muscles torque and power with isometric and isokinetic tests in older men (M) and women (W), with normal range (NW) of body mass index (BMI) and OB.

SUBJECTS/METHODS

In 70 sedentary older M and W (69 ± 5 years), NW and OB (i.e. BMI < 30 kg m^-2 and ≥30 kg m^-2, respectively) we tested the right knee's extensor: (i) isometric torque at 30°, 60°, 75° and 90° knee angles, and (ii) isokinetic concentric torque at 60, 90, 150, 180 and 210° s^-1 angular speeds. Maximal isometric T-angle, maximal isokinetic knee-extensor torque-velocity, theoretical maximal shortening velocity, maximal power, optimal torque and velocity were determined in absolute units, normalised by body mass (BM) and right leg lean mass (LLM_R) and compared over sex, BMI categories and angle or angular speeds by three-way ANOVA.

RESULTS

In absolute units, relative to BM and LLM_R, sex differences were found in favour of M for all parameters of muscle function (main effect for sex, p < 0.05). OB did not affect either absolute or relative to LLM_R isometric and isokinetic muscle function (main effect for BMI, p > 0.05); however, muscle function indices, when adjusted for BM, were lower in both M and W with OB compared to NW counterparts (p < 0.05).

CONCLUSIONS

We confirmed sex differences in absolute, relative to BM and LLM_R muscle function in favour of men. While overall muscle function and muscle contractile quality is conserved in individuals with class I OB, muscle function normalised for BM, which defines the ability to perform independently and safely the activities of daily living, is impaired in comparison with physiological ageing.

Post-Exercise Ketosis, Salivary Uric Acid and Interleukin-6 after a Simulated Wheelchair Basketball Match

BACKGROUND

Interleukin (IL)-6, total antioxidant capacity (TAC) and uric acid (UA) increase after exercise in able-bodied individuals. Wheelchair Basketball Athletes (WBA), having low muscle mass, could be at risk of post-exercise ketosis. <p >Objective: This study aimed to evaluate the post-exercise ketosis, IL-6 and antioxidant response, in WBA of the Italian National team, after a simulated match.

METHODS

Dietary intakes, Starvation Symptoms Inventory (SSI), percentage of fat mass (FM%) and basal Respiratory Exchange Ratio (RER) and Basal Energy Expenditure (BEE), were evaluated. Salivary TAC, UA and IL-6 were measured: before (PreM), at the end (EM) and 20 minutes after (PostM) the match. Capillary glucose and β-hydroxybutyrate (βHB) were monitored. Percentage of Heart Rate Reserve (%HRR) was measured to evaluate exercise intensity.

RESULTS

WBA had low carbohydrates (43.5% of daily energy intake (En)) and high fat (36.3% En) intakes. The increase in UA at PostM correlated with En (0.810, p<0.01) and was inversely related to βHB at EM (-0.719, p<0.05). Furthermore, at PostM growing IL-6 levels correlated with BEE (0.778, p<0.05) and inversely related to FM% (-0.762, p<0.5) were found, which in turn was correlated to SSI (0.781, p<0.05). Also βHB PostM correlated with SSI (0.761, p<0.05) but was inversely related to RER (-0.745, p<0.05) and En (-0.826, p<0.01).

CONCLUSIONS

Our study suggests that some WBA should improve their dietary habit in order to prevent post-exercise ketosis and ameliorate the endogenous antioxidant response after exercise.

Anthropometric Prediction of DXA-Measured Percentage of Fat Mass in Athletes With Unilateral Lower Limb Amputation

To date there is no anthropometric equation specific to athletes with unilateral lower limb amputation to estimate the percentage of fat mass (%FM). This study investigated the accuracy of a set of anthropometric equations validated on able-bodied populations to predict the %FM assessed by-means of dual-energy x-ray absorptiometry (DXA) in athletes with unilateral lower limb amputation. Furthermore, a predictive anthropometric equation specific to athletes with unilateral lower limb amputation was developed from skinfold thickness measurements using DXA as the reference method for the estimation of the %FM. Twenty-nine white male athletes with unilateral lower limb amputation underwent a DXA scan and an anthropometric assessment on the same day. The %FM, calculated through several existing anthropometric equations validated upon able-bodied populations, was compared with the DXA-measured %FM (%FM_DXA). Accuracy and agreement between the two methods was computed with two-tailed paired-sample t-test, concordance correlation coefficient, reduced major axis regression and Bland-Altman analysis. A stepwise multiple regression analysis with the %FM_DXA as the dependent variable and age and nine skinfold thicknesses as potential predictors was carried out and validated using a repeated 10-fold cross-validation. A linear regression analysis with the sum of nine skinfolds as the independent variable was also carried out and validated using a repeated 10-fold cross-validation. The results showed that the anthropometric equations validated on able-bodied populations are inaccurate in the estimation of %FM_DXA with an average bias ranging from 0.51 to -13.70%. Proportional bias was also found revealing that most of the anthropometric equations considered, tended to underestimate/overestimate the %FM_DXA as body fat increased. Regression analysis produced two statistically significant models (P < 0.001 for both) which were able to predict more than 93% of total variance of %FM_DXA from the values of four skinfold measurements (i.e., thigh, abdominal, subscapular and axillary skinfold measurements) or from the sum of 9 skinfolds. Repeated cross-validation analysis highlighted a good predictive performance of the proposed equations. The predictive equations proposed in this study represent a useful tool for clinicians, nutritionists, and physical conditioners to evaluate the physical and nutritional status of athletes with unilateral lower limb amputation directly in the field.

Different amount of training affects body composition and performance in High-Intensity Functional Training participants

The effects of High-Intensity Functional Training (HIFT) on body composition and the relationship of the latter with performance are not well defined. In this work we investigated, by means of Dual-energy X-ray Absorptiometry, the relative proportions of fat-, lean soft tissue-, and mineral mass in CrossFit^® (CF, a popular mode of HIFT) participants (n = 24; age, 28.2 ± 3.39 y; BMI, 25.3 ± 2.04 kg/m²) with at least 1 year of CF training experience and weekly amount of training > 10 h/w (n = 13; Higher Training, HT) or < 10 h/w (n = 11; Lower Training, LT) as well as age- matched and BMI-matched physically active controls (CHT, CLT). Performance was assessed in the “Fran” workout. Data were analyzed by one-way or repeated measures ANOVA where needed. Association between variables was assessed with the Pearson’s correlation coefficient r. Partial correlation was used where needed. Results showed that HT performed better than LT in the “Fran” (P < 0.001) and they had higher whole-body bone mineral density (P = 0.026) and higher lean soft mass (P = 0.002), and borderline lower percent fat mass (P = 0.050). The main difference between CF participants (HT, LT) and their respective controls (CHT, CLT) was a lower adiposity in the former. In CF participants, performance positively correlated with appendicular lean soft tissue mass (P = 0.030). It can be concluded that, in CF participants, a higher amount of weekly training improves most notably lean body mass and increases performance in association with increased skeletal muscle mass. CF participation is especially effective in reducing fat mass vs. age- and BMI-matched physically active controls.

Body composition assessment in athletes with physical impairment who have been practicing a wheelchair sport regularly and for a prolonged period

BACKGROUND

Today several important aspects related to the impact of long-term wheelchair sports on whole-body and regional body composition in athletes with a physical impairment are poorly understood.

OBJECTIVE

This cross-sectional study aimed at investigating the impact of the long-term regular practice of wheelchair sports on body composition in male wheelchair athletes (WA) as compared with both non-athletic participants with a physical impairment and non-athletic able-bodied participants.

METHODS

Nine WA were each matched pairwise by age, duration of injury and body mass index (BMI) with a participant with a physical impairment not engaged in any wheelchair sport (N-WA) and by age and BMI with an able-bodied (AB) participant. Whole-body and regional bone mineral content (BMC), fat-free soft tissue mass (FFSTM), fat mass (FM) and percentage FM (%FM) were assessed by means of Dual-Energy X-ray Absorptiometry.

RESULTS

WA had significantly lower FM and %FM vs. N-WA at the whole-body level (P = 0.01 for both) and in the trunk region (P = 0.001 and P = <0.001, respectively). The only difference in body composition variables between WA and AB was found in the legs where WA had significantly higher FM (P = 0.014) along with lower BMC (P = 0.009) and FFSTM (P = 0.005) vs. AB in the legs.

CONCLUSIONS

The results of the present study showed that the regular, long-term practice of wheelchair sport may be associated with beneficial body composition adaptations in athletes with a physical impairment at the whole-body and trunk level.

The role of age, sex, anthropometry, and body composition as determinants of physical fitness in nonobese children aged 6-12

Purpose

The determinants of physical fitness in children have been given limited attention. In particular, the relative role of chronological age, sex, anthropometry, and body composition in physical fitness of children has been barely investigated. This cross-sectional study investigated determinants of physical fitness using a set of predictive variables including, in addition to chronological age and sex, a large panel of anthropometric measurements as well as body composition. The study was carried out in a convenience sample of children aged 6–12 participating in a summer camp.

Methods

One-hundred-ninety-three children (128 males) fulfilled all requirements and entered analysis. Health-related physical fitness components (speed, muscular power and balance) were explored by means of field tests, namely the 30-m dash test for running speed, the standing long jump and the seated chest pass test for lower limbs and upper body muscular power, respectively, and the flamingo balance test for static balance. Determinants of physical fitness were investigated by regression analysis using chronological age, sex, anthropometry, and body composition in a hierarchical approach. To minimize the expected effect of collinearity in predictor variables, an original statistical approach using Random Forests analysis was adopted.

Results

Age predicted 45.2%, 43.6%, 35.6% and 25.6%; and sex 9.5%, 10.7%, 6.3% and 2.0% of variance in the 30-m dash, seated chest pass, standing long jump, and flamingo balance test, respectively. Anthropometry and body composition explained a limited or no percentage of variance. The adjusted R² (root mean square error) was 0.61 (0.31 s), 0.45 (0.32 m), 0.58 (0.15 m) and 0.41 (0.75 logs) for the 30-m dash, seated chest pass, standing long jump, and flamingo balance test, respectively making these models useful when physical fitness tests are not feasible.

Conclusions

We highlighted the respective role of chronological age, sex, anthropometry, and body composition in physical fitness of children in the wide age range 6–12 years. Data confirm and expand on previous literature by showing with a strictly conservative statistical approach that chronological age is a main determinant of physical fitness of both boys and girls, sex playing a limited role. The role of anthropometry was even less important, and no role was found for body composition. These findings should be considered when planning/implementing motor development or physical education programs.

Are body circumferences able to predict strength, muscle mass and bone characteristics in obesity? A preliminary study in women

Measurement of body circumferences (BCs) is widely used as an anthropometric tool to assess body composition and health risk in obese individuals. In this preliminary work we evaluated the association of several BCs with Dual-energy X-ray Absorptiometry (DXA)-measured lean mass as well as leg press test scores with an aim at exploring the potential of BCs as predictor of body composition and muscle strength. A total of 34 female participants aged 47.3±7.6 y who were obese (BMI, 30.4-43.7 kg/m2) were recruited. The upper arm (relaxed), wrist, chest, waist, hip, thigh, and calf circumferences were measured. The skinfold-corrected muscle (including bone) circumferences at the arm, thigh, and calf site were also calculated. Lean mass components were measured by DXA with a Hologic QDR Explorer scanner according to the manufacturer's procedures. Lower limbs strength was assessed with the 1-Repetition Maximum leg press. Bivariate association between variables was assessed with the Spearman's correlation coefficient after the Benjamini and Hochberg False Discovery Rate procedure. Predictive equations were developed using stepwise multiple regression analysis. Several statistically significant correlations (Benjamini and Hochberg corrected P [Pc] < 0.05) were present between BCs and DXA-measured body composition variables, and leg press test scores with special regard to the chest, arm, waist, and hip circumferences. Multiple regression analysis yielded statistically significant predictive models (Pc < 0.05 for all; adjusted R2 ranging 0.123 - 0.504; standard error of the estimate ranging 4.0% - 11% of the mean measured value) for all body composition as well as leg press outcomes. The current findings show that BCs represent a simple, suitable anthropometric measurement with a potential to predict several lean mass components as well as lower limbs strength in obese females. The proposed predictors need to be validated in a larger sample of participants and in obese males.

Neuromuscular and Muscle Metabolic Functions in MELAS Before and After Resistance Training: A Case Study

Mitochondrial encephalomyopathy, lactic acidosis, and recurrent stroke-like episodes syndrome (MELAS) is a rare degenerative disease. Recent studies have shown that resistant training (RT) can ameliorate muscular force in mitochondrial diseases. However, the effects of RT in MELAS are unknown. The aim of this case report was to investigate the effects of RT on skeletal muscle and mitochondrial function in a 21-years old patient with MELAS. RT included 12 weeks of RT at 85% of 1 repetition maximum. Body composition (DXA), in vivo mitochondrial respiration capacity (mVO₂) utilizing Near-infrared spectroscopy on the right plantar-flexor muscles, maximal voluntary torque (MVC), electrically evoked resting twitch (EET) and maximal voluntary activation (VMA) of the right leg extensors (LE) muscles were measured with the interpolated twitch technique. The participant with MELAS exhibited a marked increase in body mass (1.4 kg) and thigh muscle mass (0.3 kg). After the training period MVC (+5.5 Nm), EET (+2.1 N⋅m) and VMA (+13.1%) were ameliorated. Data of mVO₂ revealed negligible changes in the end-exercise mVO₂ (0.02 mM min^-1), Δ mVO₂ (0.09 mM min^-1), while there was a marked amelioration in the kinetics of mVO₂ (τ mVO₂; Δ70.2 s). This is the first report of RT-induced ameliorations on skeletal muscle and mitochondrial function in MELAS. This case study suggests a preserved plasticity in the skeletal muscle of a patient with MELAS. RT appears to be an effective method to increase skeletal muscle function, and this effect is mediated by both neuromuscular and mitochondrial adaptations.

Anthropometric prediction of DXA-measured body composition in female team handball players

Background

The relevance of body composition (BC) to performance in sport has long been appreciated with special concern on the total and regional proportion of fat and muscle. Dual-energy X-ray absorptiometry (DXA) is able to accurately measure BC, but it may not be easily available in practice; anthropometry has long been used as a simple and inexpensive field method to objectively assess BC. The aim of this study was twofold: first, to develop and validate a sport-specific anthropometric predictive equation for total body fat mass (FM) and lean mass components in female handball players to be used in the sport setting; second, to cross-validate in female team handball players several independently developed, predictive equations for BC in female athletes.

Methods

A total of 85 female team handball players (30 wings, 31 backs, 14 pivots, 10 goalkeepers) of different competitive levels underwent anthropometry and a whole-body DXA scan. Multiple linear regression analysis was used to develop predictive equations in a derivation sample (n = 60) of randomly selected players using demographic and anthropometric variables. The developed equations were used to predict DXA outcomes in an independent validation sample (n = 25).

Results

Statistically significant (P < 0.001) models were developed for total body FM (adjusted R² = 0.943, standard error of the estimate, SEE = 1,379 g), percentage FM (adjusted R² = 0.877, SEE = 2.00%), fat-free soft tissue mass (FFSTM) (adjusted R² = 0.834, SEE = 2,412 g), fat-free mass (FFSTM + bone mineral content; adjusted R² = 0.829, SEE = 2,579 g). All models were robust to collinearity. Each developed equation was successfully validated in the remaining 25 players using correlation analysis, mean signed difference, t-test, and Bland–Altman plot. The whole dataset of team handball players (n = 85) was used to cross-validate several predictive equations independently developed by others in female athletes. Equations significantly (P < 0.001 for all; t-test) over- or underestimated the corresponding DXA measurements.

Discussion

It is concluded that in team female handball players the anthropometric equations presented herein are able to estimate body fat and FFSTM with accuracy. Several BC predictive anthropometric equations developed in different female athletic populations revealed inaccurate when tested in team handball players. These results should be of use for coaches, physical trainers, and nutritionists when evaluating the physical status of female team handball players.

Anthropometry, Body Composition, and Performance in Sport-Specific Field Test in Female Wheelchair Basketball Players

Data on the physical and performance characteristics of female wheelchair basketball (WB) players are scarce. In several countries female WB players train and compete with male players on mixed teams due to the limited total population of players, which would otherwise lead to large territorial spread for each team. Any differences in terms of physical characteristics and/or WB skill proficiency between male and female WB players would be relevant to team performance in mixed teams. This work examined anthropometry, body composition, and performance in a set of sport-specific field tests in a sample of 13 female WB players representing about 40% of the eligible population in Italy across a range of functional point scores (Point). Point is assigned on an ordinal scale from 1.0 (i.e., players with minimal functional potential) through to 4.5 (players with maximum functional potential). Our female sample was then compared against twice as many (n = 26) Point-matched (±0.5 points) male players. The two groups were similar for age (P = 0.191; effect size [d] = 0.2), self-reported duration of injury (P = 0.144, d = 0.6), WB experience (P = 0.178, d = 0.5), and volume of training (P = 0.293, d = 0.4). The large majority of measured linear anthropometric variables (10/13) were lower in female players than males (0.001 < P ≤ 0.041). Skinfold-estimated percent body fat was higher (+7.6%) in females (30.7 ± 6.0%; P < 0.001, d = 1.3). Mean performance was worse in female than in males in six out of seven sport-specific field tests, scores being significantly lower in females for the maximal pass (7.5 ± 2.0 m for females vs. 10.4 ± 2.8 m for males; P = 0.002, d = 1.2) and suicide tests (55.8 ± 6.4 s for females vs. 45.4 ± 6.7 s for males; P < 0.001, d = 1.6). When performance in subgroups of females (n = 9) chosen across a range of Point was compared with that of males assigned 1.0 or 1.5 Point less (each n = 9), performance differences between male and female WB players were partially and completely eliminated, respectively. This work contributed new data for characterizing the physique and performance of female WB players. Further, the results suggested that when male and female athletes compete together in mixed teams, a 1.5 points subtraction from female players is needed to match the real gender difference in performance.

Metabolic effect of bodyweight whole-body vibration in a 20-min exercise session: A crossover study using verified vibration stimulus

The ability of whole body vibration (WBV) to increase energy expenditure (EE) has been investigated to some extent in the past using short-term single exercises or sets of single exercises. However, the current practice in WBV training for fitness is based on the execution of multiple exercises during a WBV training session for a period of at least 20 min; nevertheless, very limited and inconsistent data are available on EE during long term WBV training session. This crossover study was designed to demonstrate, in an adequately powered sample of participants, the ability of WBV to increase the metabolic cost of exercise vs. no vibration over the time span of a typical WBV session for fitness (20 min). Twenty-two physically active young males exercised on a vibration platform (three identical sets of six different exercises) using an accelerometer-verified vibration stimulus in both the WBV and no vibration condition. Oxygen consumption was measured with indirect calorimetry and expressed as area under the curve (O_2(AUC)). Results showed that, in the overall 20-min training session, WBV increased both the O_2(AUC) and the estimated EE vs. no vibration by about 22% and 20%, respectively (P<0.001 for both, partial eta squared [η²] ≥0.35) as well as the metabolic equivalent of task (+5.5%, P = 0.043; η² = 0.02) and the rate of perceived exertion (+13%, P<0.001; ŋ² = 0.16). Results demonstrated that vibration is able to significantly increase the metabolic cost of exercise in a 20-min WBV training session.

Comparison between dual-energy X-ray absorptiometry and skinfold thickness in assessing body fat in overweigh/obese adult patients with type-2 diabetes

Percentage of body fat (%BF) is estimated in clinical practice using anthropometric equations, but little is known about their reliability in overweight/obese patients with type-2 diabetes. The aim of this study was to compare, in overweight/obese adults with type-2 diabetes, %BF estimated with several commonly used anthropometric equations and %BF measured with dual-energy X-ray absorptiometry (DXA, Hologic). The %BF was measured with DXA in 40 patients aged 40-68 years with type-2 diabetes (mean HbA1c, 7.3 ± 0.9%). Body density was estimated in the same patients by means of four anthropometric equations and converted to %BF using the Siri and Brozek equations. Paired-sample t-test and the mean signed difference procedure were used to compare anthropometric equation-derived %BF and DXA measurements. The coefficient of determination was computed. Bland-Altman analysis was used to test the agreement between methods. Among the four anthropometric equations, the Durnin-Womersley equation only showed close agreement with DXA in both female and male patients; the other equations significantly underestimated or overestimated %BF. Two new predictive equations were developed using DXA as the reference to predict total body and trunk %BF. Further comparative studies are required to confirm and refine the accuracy of practical, non-invasive methods for monitoring %BF in this population.

Hydropeaking mitigation project on a multi-purpose hydro-scheme on Valsura River in South Tyrol/Italy

A hydropeaking mitigation project on Valsura River in the Italians Alps is described. The project is of particular interest due to several aspects. First of all, the Valsura torrent has unique morphological braiding characteristics, which are unique in the reach of Adige valley between Merano and Bolzano, and has a good reproduction potential for fish, especially in the terminal stretch along a biotope before its confluence with Adige River. Moreover, the Valsura hydropower cascade, which overall consists of six high-head hydropower plants, has an exceptional economic importance for the local hydropower industry. Lastly, the last HPP on the cascade is a multipurpose plant, so that interesting interactions between hydropeaking mitigation, irrigation supply and peak energy production are considered. The project started from a hydrological and a limnological measuring campaign and from an energetic, hydraulic and legislative framework analysis. The ecological findings are combined into a deficit analysis, founding the basis for the definition of a hydrological target state, which points to achieve a good natural reproduction for brown trout in the hydropeaked stretch, fulfilling at the same time the human safety conditions. Finally, mitigation Measures are described that at the same time comply with the following manifold aspects: a. maintenance of the requested target limits for fish reproduction; b. maintenance of the water release for the agricultural irrigation; c. enhancement of the flexibility of the hydropower plant's operation; d. reduction of the risk for local population. The paper compares operational and constructive mitigation measures and shows that constructive hydropeaking mitigation measures, for the present case study, can combine the positive effects of ecological improvement with higher safety standards and more flexible energy production.

The role of 3D-hydraulics in habitat modelling of hydropeaking events

One way to study ecological implications induced by hydropeaking represents the coupling of hydrodynamic models with habitat suitability models, in which hydrodynamic parameters are typically used to describe the physical habitat of indicator species. This article discusses the differences in habitat suitability assessment between 2D and 3D CFD modelling as input for the habitat simulation tool CASiMiR. In the first part of the article, the accuracy of the hydraulic model is evaluated by comparing the model results with laboratory (model of a laboratory channel with erodible bed) and field measurements (Valsura River, Bolzano, Italy). In the second part, the habitat suitability for the Valsura River case study (affected by hydropeaking), is analyzed comparing different approaches for the reconstruction of the velocity field (depth-averaged velocities from 2D modelling, bottom velocity field reconstruction with log-law approach from 2D modelling and bottom velocity field from 3D modelling). The results show that the habitat suitability index (HSI) using 2D or 3D hydrodynamic models can be significantly different. These differences can be ascribed to a higher capability to depict the features of the flow field with highly variable and heterogeneous boundary conditions and to the possibility to simulate the near bed hydrodynamic parameters, which are relevant for certain target species. In particular, the HSI-values using 3D hydraulics lead to larger areas of highly suitable habitats compared to 2D simulations. Moreover, considering the entire flow range of hydropeaking events, the habitat simulations with bottom flow velocities from 3D modelling provide suitable habitats over the entire flow range representing the availability of stable suitable habitats, while the habitat availability of 2D modelled flow velocity is continuously decreasing with increasing flow rates.

Physique and Performance of Young Wheelchair Basketball Players in Relation with Classification

The relationships among physical characteristics, performance, and functional ability classification of younger wheelchair basketball players have been barely investigated to date. The purpose of this work was to assess anthropometry, body composition, and performance in sport-specific field tests in a national sample of Italian younger wheelchair basketball players as well as to evaluate the association of these variables with the players' functional ability classification and game-related statistics. Several anthropometric measurements were obtained for 52 out of 91 eligible players nationwide. Performance was assessed in seven sport-specific field tests (5m sprint, 20m sprint with ball, suicide, maximal pass, pass for accuracy, spot shot and lay-ups) and game-related statistics (free-throw points scored per match, two- and three-point field-goals scored per match, and their sum). Association between variables, and predictivity was assessed by correlation and regression analysis, respectively. Players were grouped into four Classes of increasing functional ability (A-D). One-way ANOVA with Bonferroni's correction for multiple comparisons was used to assess differences between Classes. Sitting height and functional ability Class especially correlated with performance outcomes, but wheelchair basketball experience and skinfolds did not. Game-related statistics and sport-specific field-test scores all showed significant correlation with each other. Upper arm circumference and/or maximal pass and lay-ups test scores were able to explain 42 to 59% of variance in game-related statistics (P<0.001). A clear difference in performance was only found for functional ability Class A and D.

CONCLUSION

In younger wheelchair basketball players, sitting height positively contributes to performance. The maximal pass and lay-ups test should be carefully considered in younger wheelchair basketball training plans. Functional ability Class reflects to a limited extent the actual differences in performance.

Kinematic analysis of the wheelchair tennis serve: Implications for classification

The aim of the present study was to assess the validity of the classification system used in Open-class wheelchair tennis by investigating the relationship between post-impact ball velocity in the serve (measured using a sports radar gun) and the severity of impairment. Shoulder and wrist angles at the instant of ball impact were also estimated from 2D motion analysis. Forty-three nationally ranked Italian Open-class wheelchair tennis players were assigned to four groups (A–D) according to descending level of activity limitation. Ten successful flat serves (WFSs) and 10 successful kick serves (WKSs) for each player were recorded. One-way ANOVA showed that the severity of impairment significantly (P < 0.05) affected post-impact ball velocity and shoulder angle at the instant of ball impact. Furthermore, the mean value of post-impact ball velocity in WFS increased from group A to group D, i.e., with descending level of activity limitation. The results of this cross-sectional study indicate that the severity of impairment per se is associated with velocity of the wheelchair tennis serve, suggesting that the current classification is flawed in that it overlooks the impact of severity of impairment on players' performance.

Seasonal DXA-measured body composition changes in professional male soccer players

This work investigated changes in body composition of professional soccer players attending an Italian Serie A club across the competitive season; it is original insofar as body composition was assessed at multiple time points across the season using the accurate three-compartment model provided by Dual-Energy X-Ray Absorptiometry (DXA). Thirty-one players (4 goalkeepers, 13 defenders, 8 midfielders, 6 forwards) underwent DXA and anthropometry at pre-, mid- and end-season. One operator measured whole body and regional body composition (fat mass, FM; fat-free soft tissue mass, FFSTM; mineral mass). Two players were excluded from analysis due to serious injury. Data were analysed with repeated measures ANOVA; factors were season time point and playing position. Results showed that whole-body FM and %FM significantly (P < 0.001) decrease at mid-season (-11.9%; -1.3%, respectively) and end-season (-8.3%; -0.8%, respectively) whereas FFSTM significantly (P < 0.001) increase at mid-season (+1.3%) and end-season (+1.5%). Limited, but significant changes took place in bone mineral content. Some regional (upper and lower limbs, trunk) differences in the pattern of body composition changes across the season were also found. Changes were similar for all playing positions. It was concluded that professional soccer players undergo changes in their FM, FFSTM, and mineral mass across the season with some regional variations, irrespective of the playing position. Changes are mostly positive at mid-season, possibly due to difference in training between the first and second phase of the season.