Hip adductor activations during run-to-cut manoeuvres in compression shorts: implications for return to sport after groin injury

Abstract

Athletes at high risk of groin strains in sports such as hockey and soccer often choose to wear shorts with directional compression to aid in prevention of or recovery from hip adductor strains. Large, eccentric contractions are known to result in or exacerbate strain injuries, but it is unknown if these shorts have a beneficial effect on hip adductor muscle activity. In this study, surface electromyography (EMG) of the adductor longus and ground reaction force (GRF) data were obtained simultaneously on 29 healthy individuals without previous history of serious injury while performing unanticipated 45° run-to-cut manoeuvres in a laboratory setting wearing shorts with non-directional compression (control, HeatGear, Under Armour, USA) or shorts with directional compression (directional, CoreShort PRO, Under Armour, USA), in random order. Average adductor activity in the stance leg was significantly lower in the directional condition than in the control condition during all parts of stance phase (all P < 0.042). From this preliminary analysis, wearing directional compression shorts appears to be associated with reduced stance limb hip adductor activity. Athletes seeking to reduce demand on the hip adductors as they approach full return to activities may benefit from the use of directional compression shorts.     

Improvement of cellular health indicators and muscle quality in older women with different resistance training volumes

ABSTRACT

The main purpose of this study was to compare the effects of resistance training (RT) performed with different training volumes on phase angle (PhA), body water components, and muscle quality (MQ) in untrained older adult women. A second purpose was to assess the relationship between PhA and MQ. Sixty-two older adult women (68.6 ± 5.0 years, 65.2 ± 13.3 kg, 156.1 ± 6.2 cm) were randomly assigned into one of the three groups: two training groups performed either 1 set (G1S) or 3 sets (G3S), or a control group (CG). Body water components and PhA were estimated by bioelectrical impedance (BIA). MQ was determined by dividing skeletal muscle mass estimated by dual-energy absorptiometry (DXA) by total muscle strength from three exercises. After the intervention period, both training groups demonstrated improvements (P < 0.05) when compared with CON for intracellular water, total body water, PhA, and MQ. These results suggest that RT can improve PhA, body water components, and MQ after 12 weeks of RT in untrained older women, regardless of training volume. Furthermore, changes in MQ were positively correlated with changes in PhA (r = 0.60, P < 0.01).     

Energy expenditure and dietary intake in professional football players in the Dutch Premier League: Implications for nutritional counselling

ABSTRACT

Selecting effective dietary strategies for professional football players requires comprehensive information on their energy expenditure (EE) and dietary intake. This observational study aimed to assess EE and dietary intake over a 14-day period in a representative group (n = 41) of professional football players playing in the Dutch Premier League (Eredivisie). Daily EE, as assessed by doubly labelled water, was 13.8 ± 1.5 MJ/day, representing a physical activity level (PAL) of 1.75 ± 0.13. Weighted mean energy intake (EI), as assessed by three face-to-face 24-h recalls, was 11.1 ± 2.9 MJ/day, indicating 18 ± 15% underreporting of EI. Daily EI was higher on match days (13.1 ± 4.1 MJ) compared with training (11.1 ± 3.4 MJ; P < 0.01) and rest days (10.5 ± 3.1 MJ; P < 0.001). Daily carbohydrate intake was significantly higher during match days (5.1 ± 1.7 g/kg body mass (BM)) compared with training (3.9 ± 1.5 g/kg BM; P < 0.001) and rest days (3.7 ± 1.4 g/kg BM; P < 0.001). Weighted mean protein intake was 1.7 ± 0.5 g/kg BM. Daytime distribution of protein intake was skewed, with lowest intakes at breakfast and highest at dinner. In conclusion, daily EE and PAL of professional football players are modest. Daily carbohydrate intake should be increased to maximize performance and recovery. Daily protein intake seems more than adequate, but could be distributed more evenly throughout the day.     

Does self-determined motivation interact with environmental contexts to influence moderate-to-vigorous physical activity during a girls’ youth sport camp?

ABSTRACT

Objective: To explore whether basketball player’s self-determined motivation interacts with environmental contexts and coach training to influence percentage time in moderate-to-vigorous physical activity (%MVPA). Methods: A secondary analysis of data from 76 girls (mean ± SD, 10.5 ± 1.0 years) was conducted. Players were classified as high self-determined motivation (HSDM) or low self-determined motivation (LSDM) and randomised to trained (intervention) or untrained (control) coaches. Training included 2 workshops on strategies for activity-promoting practices. Girls were exposed to environmental contexts (practices and games) led by a trained/untrained coach (depending on arm) and one without coaches (free time) daily. Girls wore accelerometers each day. Using mixed random-effects models, the influence of motivation, context and training on %MVPA was analysed. Results: Trained coaches’ practices were associated with the greatest %MVPA with no difference between HSDM and LSDM players (38.28 ± 1.77%; 37.64 ± 1.80%; p = 0.66). HSDM players had significantly greater %MVPA versus LSDM players during untrained coaches’ practices (23.58 ± 1.77%; 20.51 ± 1.78%; p = 0.03). During games with trained coaches, HSDM players had greater %MVPA compared to LSDM players (23.79 ± 1.76%; 18.56 ± 1.74%; p < 0.001). No between-group difference in %MVPA during free time was found (12.85 ± 0.82%; 13.39 ± 0.84%; p = 0.64). Conclusion: The impact of individual differences in self-determined motivation on %MVPA during practices was attenuated when coaches were trained to implement activity-promoting practices.     

Do habitual foot-strike patterns in running influence functional Achilles tendon properties during gait?

ABSTRACT

The capacity of foot-strike running patterns to influence the functional properties of the Achilles tendon is controversial. This study used transmission-mode ultrasound to investigate the influence of habitual running foot-strike pattern on Achilles tendon properties during barefoot walking and running. Fifteen runners with rearfoot (RFS) and 10 with a forefoot (FFS) foot-strike running pattern had ultrasound transmission velocity measured in the right Achilles tendon during barefoot walking (≈1.1 ms^?1) and running (≈2.0 ms^?1). Temporospatial gait parameters, ankle kinematics and vertical ground reaction force were simultaneously recorded. Statistical comparisons between foot-strike patterns were made using repeated measure ANOVAs. FFS was characterised by a significantly shorter stance duration (?4%), greater ankle dorsiflexion (+2°), and higher peak vertical ground reaction force (+20% bodyweight) than RFS running (P < .05). Both groups adopted a RFS pattern during walking, with only the relative timing of peak dorsiflexion (3%), ground reaction force (1–2%) and peak vertical force loading rates (22–23%) differing between groups (P < .05). Peak ultrasound transmission velocity in the Achilles tendon was significantly higher in FFS during walking (≈100 ms^?1) and running (≈130 ms^?1) than RFS (P < .05). Functional Achilles tendon properties differ with habitual footfall patterns in recreational runners.     

Nutritional strategies for promoting fat utilization and delaying the onset of fatigue during prolonged exercise

Carbohydrate ingestion before and during endurance exercise delays the onset of fatigue (reduced power output). Therefore, endurance athletes are recommended to ingest diets high in carbohydrate (70% of total energy) during competition and training. However, increasing the availability of plasma free fatty acids has been shown to slow the rate of muscle and liver glycogen depletion by promoting the utilization of fat. Ingested fat, in the form of long-chain (C 16-22 ) triacylglycerols, is largely unavailable during acute exercise, but medium-chain (C 8-10 ) triacylglycerols are rapidly absorbed and oxidized. We have shown that the ingestion of medium-chain triacylglycerols in combination with carbohydrate spares muscle carbohydrate stores during 2 h of submaximal (< 70% VO 2 peak) cycling exercise, and improves 40 km time-trial performance. These data suggest that by combining carbohydrate and medium-chain triacylglycerols as a pre-exercise supplement and as a nutritional supplement during exercise, fat oxidation will be enhanced, and endogenous carbohydrate will be spared. We have also examined the chronic metabolic adaptations and effects on substrate utilization and endurance performance when athletes ingest a diet that is high in fat (> 70% by energy). Dietary fat adaptation for a period of at least 2-4 weeks has resulted in a nearly two-fold increase in resistance to fatigue during prolonged, low- to moderate-intensity cycling (< 70% VO 2 peak). Moreover, preliminary studies suggest that mean cycling 20 km time-trial performance following prolonged submaximal exercise is enhanced by 80 s after dietary fat adaptation and 3 days of carbohydrate loading. Thus the relative contribution of fuel substrate to prolonged endurance activity may be modified by training, pre-exercise feeding, habitual diet, or by artificially altering the hormonal milieu or the availability of circulating fuels. The time course and dose-response of these effects on maximizing the oxidative contribution of fat for exercise metabolism and in exercise performance have not been systematically studied during moderate- to high-intensity exercise in humans.     

Influence of birth quarter on the rate of physical activities and sports participation

Abstract

The purpose of this study was to assess the potential influence of birth quarter on the frequency of physical activity and participation in specific activities during adulthood. We used data from one national and one provincial survey, the 2005 Canadian Community Health Survey and the 1998 Quebec Social and Health Survey (Enquête sociale et de santé du Québec) respectively. We analysed the distribution of participants at each level of practice of a given leisure activity and work-related physical activity. In the Canadian Community Health Survey, a relative age effect was found for participation in soccer in the 25- to 60-year-old population. However, for volleyball, a significant relative age effect was also observed but with over-representation of the last quarters of the year for the whole population and for men aged 12–60 years. In the Quebec Social and Health Survey, significant differences in the frequency of distribution without a relative age effect were revealed for participation in women's ice hockey, work-related physical activity level, and stage of change for physical activity. Overall, the data indicate that the systematic relative age effect reported in other studies for some competitive sports, such as ice hockey and soccer, is not as prevalent in leisure physical activities during adulthood. This may reflect lower competitive selection and attrition in population physical activity compared with competitive sports in younger athletes.