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The purpose of this study was to compare court-movement variables and physiological responses to wheelchair tennis match-play when using low vs. standard compression tennis balls. Eleven wheelchair basketball players were monitored during repeated bouts of tennis (20 min) using both ball types. Graded and peak exercise tests were completed. For match-play, a data logger was used to record distance and speed. Individual linear heart rate oxygen consumption relationships were used to estimate match-play oxygen uptake. Significant main effects for ball type revealed that total distance (P < 0.05), forward distance (P < 0.05), and average speed (P < 0.05) were higher for play using a low-compression ball. A lower percentage of total time was spent stationary (P < 0.001), with significantly more time spent at speeds of 1--1.49 (P < 0.05), 1.5--1.99 (P < 0.05) and 2.0--2.49 (P < 0.05) m•sec-1 when using the low-compression ball. Main effects for physiological variables were not significant. Greater total and forward distance, and higher average speeds are achieved using a low-compression ball. The absence of any difference in measured HR and estimated physiological responses would indicate that players move further and faster at no additional mean physiological cost. This type of ball will be useful for novice players in the early phases of skill development. [ABSTRACT FROM AUTHOR]

To compare the force application characteristics at various push frequencies of asynchronous (ASY) and synchronous (SYN) hand-rim propulsion, 8 able-bodied participants performed a separate sub-maximal exercise test on a wheelchair roller ergometer for each propulsion mode. Each test consisted of a series of 5, 4-min exercise blocks at 1.8 m⋅s-1 - initially at their freely chosen frequency (FCF), followed by four counter-balanced trials at 60, 80, 120 and 140 % FCF. Kinetic data was obtained using a SMARTWheel , measuring forces and moments. The gross efficiency (GE) was determined as the ratio of external work done and the total energy expended. The ASY propulsion produced higher force measures for FRES, FTAN, rate of force development & FEF (P < 0.05), while there was no difference in GE values (P = 0.518). In pair-matched push frequencies (ASY80:SYN60, ASY100:SYN80, ASY120:SYN100 and ASY140:SYN120), ASY propulsion forces remained significantly higher (FRES, FTAN, rate of force development & FEF (P < 0.05), and there was no significant effect on GE (P = 0.456). Both ASY and SYN propulsion demonstrate similar trends: changes in push frequency are accompanied by changes in absolute force even without changes in the gross pattern/trend of force application, FEF or GE. Matched push frequencies continue to produce significant differences in force measures but not GE. This suggests ASY propulsion is the predominant factor in force application differences. The ASY would appear to offer a kinetic disadvantage to SYN propulsion and no physiological advantage under current testing conditions. [ABSTRACT FROM AUTHOR]

This study examined the effect of rear-wheel camber on maximal effort wheelchair mobility performance. 14 highly trained wheelchair court sport athletes performed a battery of field tests in 4 standardised camber settings (15 °, 18 °, 20 °, 24 °) with performance analysed using a velocometer. 20 m sprint times reduced in 18 ° (5.89 ± 0.47 s, P = 0.011) and 20 ° camber (5.93 ± 0.47 s, P = 0.030) compared with 24 ° (6.05 ± 0.45 s). Large effect sizes revealed that 18 ° camber enabled greater acceleration over the first 2 (r = 0.53, 95 % CI = 0.004 to 0.239) and 3 (r = 0.59, 95 % CI = 0.017 to 0.170) pushes compared with 24 °. Linear mobility times significantly improved (P ≤ 0.05) in 15 ° (16.08 ± 0.84 s), 18 ° (16.06 ± 0.97 s) and 20 ° (16.22 ± 0.84 s) camber compared with 24 ° (16.62 ± 1.10 s). Although no statistically significant main effect of camber was revealed, large effect sizes (r = 0.72, 95 % CI = 0.066 to 0.250) demonstrated that 18 ° camber reduced times taken to perform the manoeuvrability drill compared with 15 °. It was concluded that 18 ° camber was the best performing setting investigated given its superior performance for both linear and nonlinear aspects of mobility, whereas 24 ° camber impaired linear performance. This was likely to be due to the greater drag forces experienced. Subsequently, athletes would be recommended to avoid 24 ° camber and young or inexperienced athletes in particular may benefit from selecting 18 ° as a starting point due to its favourable performance for all aspects of mobility performance in the current study. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyse adaptations in propulsion technique and gross efficiency in novice able-bodied subjects during the initial phase of learning hand-rim wheelchair propulsion to music. 22 able bodied participants performed wheelchair propulsion (1.1 m⋅s-1) followed by a VO2 peak test on a wheelchair ergometer. Push frequency, gross efficiency (GE), heart rate, rating of perceived exertion and propulsion technique variables (force application and temporal characteristics) were recorded. Participants were then assigned to a 3-wk practice period listening to i) 125 beats-min-1 tempo music (LOW); ii) 170 beats-min-1 tempo music (HIGH); or iii) a control group (CON). Following practice, all participants repeated the pre-testing protocol whilst force application data was collected in practice trials 1 and 9. After accounting for the pre-practice differences in GE (using ANCOVA), GE was higher in LOW compared with CON (P=0.038; 6.6 vs. 6.1% respectively). The differences between CON vs. HIGH and LOW vs. HIGH (P=0.830; P=0.188) were trivial suggesting that only LOW experienced an increase in GE. Practice had a favourable effect on the perceptions of effort, work per cycle, push and cycle time in contrast to the CON group. The use of music in a rehabilitation setting warrants further investigation. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effects of 60-min bouts of intermittent moderate and vigorous exercise on postprandial plasma triacylglycerol (TAG) metabolism in eight healthy adolescent boys (mean +/- SD age: 13 +/- 0.3 yr). Methods: Participants completed three conditions in a counterbalanced order. On day 1, they either rested for 110 min (CON), completed 6 x 10-min blocks of intermittent treadmill exercise at 53% peak V[spacing dot above]O2 (MOD), or 6 x 10-min blocks at 75% peak V[spacing dot above]O2 (VIG). On day 2 after a 12-h fast, a capillary blood sample was taken for [TAG] and [glucose] (mmol[middle dot]L-1) and then a high-fat milkshake was consumed (1.50 g[middle dot]kg-1 fat, 1.22 g[middle dot]kg-1 CHO, and 0.22 g[middle dot]kg-1 protein; 80 kJ[middle dot]kg-1). Further blood samples were taken every hour for a 6-h postprandial rest period for [TAG] and [glucose]. Results: Estimated energy expenditure was 45% higher in VIG than in MOD (95% confidence interval [CI] 23-72%). Fasting [TAG] and [glucose] did not differ between the conditions. Average [TAG] for the postprandial period was lower by 24% in MOD (95% CI -47% to 9%, P = 0.06) and by 21% in VIG (95% CI -42% to 8%, P = 0.08) than CON, with no meaningful difference (4%; 95% CI -27% to 48%, P = 0.50) between MOD and VIG. The total area under the [TAG] versus time curve (mmol[middle dot]L-1 6 h) was lower by 24% in MOD (95% CI -42% to 0%, P = 0.05) and by 20% in VIG (95% CI -37% to 0%, P = 0.07) than CON. MOD and VIG were not different from each other (4%; 95% CI -18% to 32%, P = 0.54). Conclusion: Both 60 min of moderate and vigorous intermittent exercises reduced postprandial [TAG]. However, the extra energy expended in the vigorous condition did not produce a dose-related reduction compared with the moderate-intensity condition. [ABSTRACT FROM AUTHOR]

The purpose of this study was to characterise the VO2 kinetic response to moderate intensity cycle exercise in endurance-trained (END) and sprint or power-trained (SPR) track and field master athletes ranging in age from 45 to 85 years. We hypothesised that the time constant (τ) describing the Phase II VO2 on-response would be smaller in the END compared to the SPR athletes, and that the τ would become greater with increasing age in both groups. Eighty-four master athletes who were competing at either the British or European Veteran Athletics Championships acted as subjects, and were classified as either END (800 m - marathon; n = 41), or SPR (100-400 m and field events; n = 43) specialists. Subjects completed two 6 minute "step" transitions to a work rate of moderate intensity on a cycle ergometer and pulmonary gas exchange was measured breath-by-breath. Analysis of variance revealed that SPR athletes had slower VO2 on-kinetics (i.e., greater τ) compared to END athletes at each of the age groups studied: 46-55 yrs (END: 25±6 vs. SPR: 36±9 s; p < 0.10), 56-65 yrs (END: 25 ± 5 vs. SPR: 35 ± 10 s; p < 0.05), 66-75 yrs (END: 29± 10 vs. SPR: 40±13 s; p < 0.05), and 76-85 yrs (END: 31 ± 10 vs. SPR: 51 ± 18 s; p < 0.05). The VO2 on-kinetics became slower with advancing age in the SPR athletes (p < 0.05 between 56-65 and 76-85 yrs) but were not significantly changed in the END athletes. The slower VO2 on-kinetics in SPR compared to END master athletes is consistent both with differences in physiology (e.g., muscle fibre type, oxidative/glycolytic capacity) and training between these specialist athletes. Master END athletes have similar τ values to their younger counterparts (-25 s) suggesting that participation in endurance exercise training limits the slowing of VO2 on-kinetics with age in this population. [ABSTRACT FROM AUTHOR]

PURPOSE: To study the effect of exercise volume on pre- and early-pubertal children's lipid-lipoprotein profile. METHODS: Thirty-four children (15 girls) completed 12 wk of exercise training, preceded by a 12-wk control period. Sixteen (7 girls and 9 boys) expended an additional 422 +/- 5 kJ.kg BM (LOW, 100 kcal.kg), whereas 18 (8 girls and 10 boys) expended an additional 586 +/- 7 kJ.g (MOD, 140 kcal.kg) as a result of the training program. They all exercised on three nonconsecutive days per week at 80 +/- 1% HRpeak. Exercise duration was individualized to match energy expenditure targets. Plasma TG, TC, and HDL-C were measured precontrol, pretraining, and posttraining. LDL-C, TC/HDL-C, and LDL-C/HDL-C were also calculated. RESULTS: Group mean lipid-lipoprotein concentrations did not change as a result of training energy expenditure in either of the groups (P > 0.05). Dietary composition, habitual physical activity, and body composition were also relatively stable over the intervention period (P > 0.05). In the LOW, but not the MOD group, peak VO2 (mL.kg.min) tended to increase over the intervention period (P = 0.07). Pearson's product moment correlation analyses indicated that pretraining concentrations of TG, TC, LDL-C, TC/HDL-C, and LDL-C/HDL-C were all related to the small changes seen in the lipid-lipoprotein profile (P < 0.01). CONCLUSION: Additional energy expenditure of 422 or 586 kJ.kg, as a direct result of aerobic exercise training over a 12-wk period, did not cause significant alterations in the lipid-lipoprotein profile in pre- and early-pubertal children. This may indicate that the exercise volume was insufficient, the lipoprotein profiles of the majority of children in this study were classified as 'desirable,' or more likely a combination of these factors. [ABSTRACT FROM AUTHOR]

Background: The number of girls meeting age-specific physical activity recommendations declines precipitously during adolescence. Alternative forms of accessible physical activity that may confer benefit to the long-term metabolic health of this population represents an important avenue for research. This study aimed to assess the effect of short, repeated bouts of walking and breaks in sitting time on postprandial metabolism in inactive adolescent girls. Methods: Seventeen girls (12.8 (0.4) years) completed two, 3-day experimental conditions. On each of days 1 and 2 of the physical activity condition (PA), participants completed 4 x 10 min bouts of self-paced treadmill walking and accumulated 18 x 5 min standing bouts over the course a simulated school day (07:30 to 15:30). On PA day 3, participants attended school as normal with no additional physical activity prescribed. On all 3 days of the control condition (CON), participants attended school as normal with no specific physical activity prescribed. On days 2 and 3 of both PA and CON, a capillary blood sample was provided to determine fasting [TAG] and [glucose]. Participants then consumed a standardised breakfast (0 h) and lunch (4.7 h) and blood samples were provided postprandially at 2.7, 5.3 and 7.3 h for [TAG] and [glucose]. Results: The mean 10 min, treadmill walking speed of 5.8 (0.3) km⋅h-1 elicited a heart rate of 143 beats⋅min-1 and OMNI rating of 2 (easy). Dietary intake and composition 24 h before day 1 was similar between PA and CON (ES≤0.27). Linear mixed model analyses indicated that total areas under the time curves for natural logs of triacylglycerol (TAG) and glucose were not meaningfully different between PA and CON (ES≤0.04) and the changes from day 2 to 3 were consistent between PA and CON (ES=0.10). Discussion: The combined accumulation of 260 min of walking and breaks in sitting time over two consecutive simulated school days in the PA condition was insufficient to attenuate postprandial lipaemia or glycaemia in inactive adolescent girls compared with standard school attendance (CON). Further research is required to assess the effect of long-term adherence to light activity and breaks in sitting time on postprandial metabolism. [ABSTRACT FROM AUTHOR]

Background: An acute bout of prior, moderate- to high-intensity exercise attenuates postprandial lipaemia (PPL) in young people. However, the laboratory based exercise known to induce this desirable physiological response bears little resemblance to the free living physical activities in which young people typically engage. Therefore, this study was designed to compare the effect of laboratory based treadmill exercise and free-living afterschool football activity on PPL in adolescent boys. Methods: Fifteen boys (12.6 (0.5) years) completed three, 2-day experimental conditions. On day 1, participants either: rested (CON); exercised for 48 min on a treadmill at 60% peak VO2 (TMEX); or played 48 min of 5-a-side football (FBALL). On day 2, participants attended school where a capillary blood sample was provided to determine fasting triacylglycerol concentration ([TAG]). Participants then consumed a standardised breakfast (0 h) and lunch (4.5 h) and blood samples were provided postprandially at 2.5, 5.0 and 7.0 h for [TAG]. Results: During TM-EX a heart rate of 157 (7) beats⋅min-1 was elicited and a total distance of 5.9 (0.5) km was covered. In contrast, during FBALL a heart rate of 175 (8) was elicited and a total distance of 3.5 (0.4) km was covered. Based on ratios of geometric means, fasting [TAG] was lower after TM-EX (95% CI = -27 to -2%, ES = 0.46) and FBALL (95% CI = -41 to -18%, ES = 1.00) compared with CON. Fasting [TAG] was also significantly lower in FBALL compared with TM-EX (95% CI = -25 to -5%, ES = 0.53). The total area under the [TAG] versus time curve (TAUC-TAG) was 17% lower in TM-EX vs. CON (95% CI = -29 to -4%, ES = 0.49) and 23% lower in FBALL vs. CON (95% CI = -33 to -12%, ES = 0.69). Although TAUC-TAG was 7% lower in FBALL compared with TM-EX, this difference was trivial and did not reach statistical significance (95% CI = -19 to 6%, ES = 0.19). Discussion: Small sided, afterschool football activity attenuates PPL in adolescent boys. The metabolic responses to small sided football activity are similar to those observed after laboratory-based treadmill exercise. [ABSTRACT FROM AUTHOR]

Longitudinal paediatric population studies have provided evidence that the risk factor theory may be extended to children and adolescents. These studies could assist in identifying individuals at increased coronary risk. Numerous studies have focused on the effects of regular exercise on the paediatric lipoprotein profile, a recognised primary risk factor, with equivocal results. Cross-sectional comparisons of dichotomised groups provide the strongest evidence of an exercise effect. ‘Trained’ or ‘active’ children and adolescents demonstrate ‘favourable’ levels of high density lipoprotein-cholesterol (HDL-C), triacylglycerol, total cholesterol (TC)/HDL-C and low density lipoprotein-cholesterol (LDL-C)/HDL-C, whilst TC is generally unaffected. The evidence regarding LDL-C in these studies is equivocal. A possible self-selection bias means that a cause-effect relationship between exercise and the lipoprotein profile cannot be readily established from this design. Correlational studies are difficult to interpret because of differences in participant characteristics, methods employed to assess peak oxygen uptake and habitual physical activity (HPA), and the statistical techniques used to analyse multivariate data. Directly measured cardiorespiratory fitness does not appear to be related to lipoprotein profiles in the children and adolescents studied to date, although there are data to the contrary. The relationship with HPA is more difficult to decipher. The evidence suggests that a ‘favourable’ lipoprotein profile may be related to higher levels of HPA, although differences in assessment methods preclude a definitive answer. While few prospective studies exist, the majority of these longitudinal investigations suggest that imposed regular exercise has little, if any, influence on the lipoprotein levels of children and adolescents. However, most prospective studies have several serious methodological design weaknesses, including low sample size, inadequate exercise training volume and a lack of control individuals. Recent studies have suggested that increases in HDL-C and reductions in LDL-C may be possible with regular exercise. The identification of a dose-response relationship between exercise training and the lipoprotein profile during the paediatric years remains elusive. [ABSTRACT FROM AUTHOR]

Presents a research on the contribution of physiological variables to the performance of athletes. Fitness of trained adolescents; Estimate of running speed from the regression equation; Use of finish times in competitive racing situation for performance measures.

An abstract of the article "Postprandial Triacylglycerol (TAG) Metabolism in Adolescent Boys: A Case for Moderate Intensity Exercise," by K. Tolfrey, A. Doggett et al. is presented.

In persons with a spinal cord injury (SCI), resistance training using neuromuscular electrical stimulation (NMES-RT) increases lean mass in the lower limbs. However, whether protein supplementation in conjunction with NMES-RT further enhances this training effect is unknown. In this randomized controlled pilot trial, 15 individuals with chronic SCI engaged in 3 times/week NMES-RT, with (NMES+PRO, n = 8) or without protein supplementation (NMES, n = 7), for 12 weeks. Before and after the intervention, whole body and regional body composition (DXA) and fasting glucose and insulin concentrations were assessed in plasma. Adherence to the intervention components was ≥96%. Thigh lean mass was increased to a greater extent after NMES+PRO compared to NMES (0.3 (0.2, 0.4) kg; p < 0.001). Furthermore, fasting insulin concentration and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) were decreased similarly in both groups (fasting insulin: 1 [-9, 11] pmol∙L -1 ; HOMA-IR: 0.1 [-0.3, 0.5] AU; both p ≥ 0.617). Twelve weeks of home-based NMES-RT increased thigh lean mass, an effect that was potentiated by protein supplementation. In combination with the excellent adherence and apparent improvement in cardiometabolic health outcomes, these findings support further investigation through a full-scale randomized controlled trial., (© 2024 The Author(s). Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)