Sleep restriction and degraded reaction-time performance in Figaro solo sailing races

Abstract

In solo offshore sailing races like those of the Solitaire du Figaro, sleep must be obtained in multiple short bouts to maintain competitive performance and safety. Little is known about the amount of sleep restriction experienced at sea and the effects that fatigue from sleep loss have on sailors’ performance. Therefore, we assessed sleep in sailors of yachts in the Figaro 2 Beneteau class during races and compared response times on a serial simple reaction-time test before and after races. Twelve men (professional sailors) recorded their sleep and measured their response times during one of the three single-handed races of 150, 300 and 350 nautical miles (nominally 24–50 h in duration). Total estimated sleep duration at sea indicated considerable sleep insufficiency. Response times were slower after races than before. The results suggest that professional sailors incur severe sleep loss and demonstrate marked performance impairment when competing in one- to two-day solo sailing races. Competitive performance could be improved by actively managing sleep during solo offshore sailing races.     

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).     

The effects of eccentric phase duration on concentric outcomes in the back squat and bench press in well-trained males

ABSTRACT

The velocity and magnitude in which the eccentric phase of an exercise is completed directly affects performance during the concentric phase. Therefore, the purpose of this research was to investigate the effects of eccentric phase duration on concentric outcomes at 60% and 80% of one-repetition maximum (1RM) in the squat and bench press. Sixteen college-aged, resistance-trained males completed 1RM testing, established normative eccentric durations, and performed fast (0.75 times normative) and slow (2.0 times normative) metronome-controlled eccentric duration repetitions. Outcome measures assessed during the concentric phase were: average concentric velocity (ACV), peak concentric velocity (PCV), rating of perceived exertion (RPE), range of motion (ROM), and barbell path. Eccentric duration was significantly and inversely correlated with ACV at 60% (r = ?0.408, p = 0.004) and 80% (r = ?0.477, p = 0.001) of 1RM squat. At 60% of 1RM squat, both fast and slow eccentric conditions produced greater (p < 0.001) PCV than normative duration with fast also producing greater PCV than slow (p = 0.044). Eccentric duration had no impact on RPE, ROM, or barbell path. Our results report for the first time that resistance-trained males performing a deliberately faster eccentric phase may enhance their own squat and bench press performance.     

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.     

Physiological efficiency of constant power output at varying pedal rates

Abstract

The study investigated the absolute and relative (% maximal) physiological demands of constant power output at three pedal rates chosen to incorporate the range used by racing cyclists. Following the assessment of maximal exercise capabilities utilizing a recently developed racing cycle ergometry system, ten highly trained racing cyclists undertook a randomized sequence of work bouts at low (70.0 ± 1.1), medium (94.8 ± 0.8) and high (126.5 ± 1.1) pedal rates per minute at constant power output under an unloaded (free wheel) condition and under a loaded (196.2 ± 8.0 W) condition which demanded approximately 75% VO₂ max. In both the unloaded and loaded conditions absolute cardiorespiratory demands of work at the highest pedal rate were significantly higher than those at the low and medium pedal rates (P<0.05). Similarly, the relative (% max) cardiorespiratory demands of unloaded work at the highest pedalling rate were significantly greater that at low and medium pedal rates (P < 0.05). There were clear, but nonsignificant trends of elevated relative cardiorespiratory demands during loaded work at the highest pedal rate, compared with low and medium pedal rates. Furthermore, net muscular efficiency demonstrated a significant decline (P<0.01) at the highest pedalling rate (21.2%) compared with the medium (24.0%) and low (25.6%) pedalling rates, confirming that metabolic economy of constant power output declined with increased pedalling rate under simulated racing cycling conditions.     

Aerobic exercise and type a behaviour

The Type A behaviour pattern is a well‐documented, if controversial, risk factor for coronary heart disease. Surprisingly, relatively little work has been reported on ways of modifying this behaviour pattern. Aerobic exercise, with its demonstrated benefits for both cardiovascular reactivity and psychological ‘well‐being’, is a promising treatment. The literature is reviewed and recommendations are made for practical applications and future research.     

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.     

Comparison of different theoretical models estimating peak power output and maximal oxygen uptake in trained and elite triathletes and endurance cyclists in the velodrome

Abstract

The primary objective of this study was to examine the relationship between heart rate intensity and pedometer step counts in adolescents. To determine cardiorespiratory fitness, 106 participants (47 boys, 59 girls, mean age 14.2 years, s = 0.8) completed the Queen's College Step Test and were classified as having low, moderate or high cardiorespiratory fitness. Adolescents also completed a 10-min treadmill trial while wearing a pedometer and heart rate monitor. The participants were instructed to maintain their heart rate between 65 and 75% of their maximum heart rate while running or walking on a treadmill. A heart rate of 65–75% maximum was associated with 146 steps per minute (s = 22) in boys and 137 steps per minute (s = 22) in girls. Results of analysis of variance indicated that there was a main effect for level of fitness (F _2,102 = 9.36, P < 0.001). The correlation between mean steps per minute and estimated maximum oxygen consumption was statistically significant (r = 0.44, P < 0.001). The results from this study suggest that a step rate of 130 steps per minute is equal to 65–75% maximum heart rate in low-fit adolescents and achieving 130 steps per minute could be used as an initial goal to improve fitness.     

The effect of biofeedback training on affective regulation and simulated car-racing performance: A multiple case study analysis

Abstract

In this study, we wished to investigate the factors that determine the direction of the spin axis of a pitched baseball. Nineteen male baseball pitchers were recruited to pitch fastballs. The pitching motion was recorded with a three-dimensional motion analysis system (1000 Hz), and the orientations of the hand segment in a global coordinate system were calculated using Euler rotation angles. Reflective markers were attached to the ball, and the direction of the spin axis was calculated on the basis of their positional changes. The spin axis directions were significantly correlated with the orientations of the hand just before ball release. The ball is released from the fingertip and rotates on a plane that is formed by the palm and fingers; the spin axis of the ball is parallel to this plane. The lift force of the pitched baseball is largest when the angular and translational velocity vectors are mutually perpendicular. Furthermore, to increase the lift forces for the fastballs, the palm must face home plate.