Substrate oxidation during incremental arm and leg exercise in men and women matched for ventilatory threshold

The aim of this study was to determine the variations in substrate utilization between men and women matched for ventilatory threshold (Tvent) during incremental arm cranking and leg cycling exercise at 70, 85, 100 and 115% of the mode-specific Tvent. Recreationally active men (n=12) and women (n=10) with similar values for percentage of peak oxygen consumption at Tvent participated in the study. Ventilatory equivalence, excess CO2 and modified V-slope methods were used concurrently to determine Tvent. The participants performed 5 min of exercise at each of 70, 85, 100 and 115% Tvent during both arm cranking and leg cycling exercise. The females were tested during the early follicular phase for all trials. A two-way mixed-design analysis of variance was performed to test for differences between the sexes. When carbohydrate and fat oxidation were expressed relative to total fat-free mass, carbohydrate oxidation during arm cranking and leg cycling was significantly higher in men than women at each percentage of Tvent. In contrast, women showed significantly higher fat oxidation across intensities during both arm cranking and leg cycling. Our results suggest that when substrate utilization is expressed relative to total fat-free mass, women appear to maintain a higher rate of fat and lower rate of carbohydrate oxidation than men during both incremental arm cranking and leg cycling exercise relative to Tvent.     

Substrate oxidation during incremental arm and leg exercise in men and women matched for ventilatory threshold

Abstract

The aim of this study was to determine the variations in substrate utilization between men and women matched for ventilatory threshold (T _vent) during incremental arm cranking and leg cycling exercise at 70, 85, 100 and 115% of the mode-specific T _vent. Recreationally active men (n = 12) and women (n = 10) with similar values for percentage of peak oxygen consumption at T _vent participated in the study. Ventilatory equivalence, excess CO₂ and modified V-slope methods were used concurrently to determine T _vent. The participants performed 5 min of exercise at each of 70, 85, 100 and 115% T _vent during both arm cranking and leg cycling exercise. The females were tested during the early follicular phase for all trials. A two-way mixed-design analysis of variance was performed to test for differences between the sexes. When carbohydrate and fat oxidation were expressed relative to total fat-free mass, carbohydrate oxidation during arm cranking and leg cycling was significantly higher in men than women at each percentage of T _vent. In contrast, women showed significantly higher fat oxidation across intensities during both arm cranking and leg cycling. Our results suggest that when substrate utilization is expressed relative to total fat-free mass, women appear to maintain a higher rate of fat and lower rate of carbohydrate oxidation than men during both incremental arm cranking and leg cycling exercise relative to T _vent.     

The effect of submaximal exercise on recovery hemodynamics and thermoregulation in men and women

Five women and 5 men were studied to examine the effects of submaximal exercise on thermoregulatory and hemodynamic variables during recovery in two environments: (a) control (C), 22 degrees C, 33% rh; and (b) hot humid (H), 32 degrees C. The participants exercised on a cycle ergometer at 60% of peak oxygen consumption for 35 min prior to 90 min of seated recovery. Sessions were identical, except for environment. Variables evaluated (p < .05) were: core temperature (TR), mean skin temperature (Ts), sweat rate (SR), heart rate (HR), stroke index (SI), cardiac index (CI), forearm blood flow (FBF), systolic blood pressure (SBP), and diastolic blood pressure (DBP). Men and women exhibited similar patterns of TR, Ts, and SR in both environments. Ts and SR (collapsed means for gender) were higher in the H than in the C. DBP was higher in men than in women throughout recovery in both environments. With combined means for gender, HR was higher in the H than in the C. CI, SI, FBF, and SBP were similar in both environments and returned to baseline within 15 min into recovery. These data suggest that heat dissipation during extended recovery was accomplished with similar contributions of cutaneous vasodilation and sweating in M and F. Furthermore, the moderate exercise level did not influence hemodynamics beyond 15 min of recovery in either environment.     

妇女骨质疏松症与运动

从运动对妇女骨质密度及妇女疏松症的影响方面进行文献评述,并提出了运动促进妇女骨质疏松症康复研究新建议,以期为预防和治疗骨质疏松症提供科学的参考依据。     

Intra- and inter-session reliability of vertical jump performance in healthy middle-aged and older men and women

Abstract

Despite its widespread use in performance assessment, the reliability of vertical jump in an ageing population has not been addressed properly. The aim of the present study was to assess intra- and inter-day reliability of countermovement jump in healthy middle-aged (55–65 years) and older (66–75 years) men and women. Eighty-two participants were recruited and asked to perform countermovement jumps on two different occasions interspersed by 4 weeks. The middle-aged groups exhibited excellent absolute reliability for flight height, jump height, peak force, peak power, peak force/body mass, and peak power/body mass, with coefficients of variation ranging from 2.9% to 7.2% in men and from 3.6% to 6.9% in women and moderate-to-high intraclass correlations (0.75 to 0.97 in men; 0.77 to 0.95 in women). The older groups displayed good coefficients of variation (4.2% to 10.8% in men and 3.4% to 9.5% in women), but the intraclass correlations were low-to-high (0.43 to 0.84 in men; 0.42 to 0.93 in women). Overall, intra-session reliability was higher than inter-session reliability. Peak power was by far the most consistent variable, whereas flight and jump height had the most marked variability. The minimum detectable change varied from 10.5% to 33%, depending on the variable examined, suggesting important implications for intervention studies.     

Intra- and inter-session reliability of vertical jump performance in healthy middle-aged and older men and women

Despite its widespread use in performance assessment, the reliability of vertical jump in an ageing population has not been addressed properly. The aim of the present study was to assess intra- and inter-day reliability of countermovement jump in healthy middle-aged (55-65 years) and older (66-75 years) men and women. Eighty-two participants were recruited and asked to perform countermovement jumps on two different occasions interspersed by 4 weeks. The middle-aged groups exhibited excellent absolute reliability for flight height, jump height, peak force, peak power, peak force/body mass, and peak power/body mass, with coefficients of variation ranging from 2.9% to 7.2% in men and from 3.6% to 6.9% in women and moderate-to-high intraclass correlations (0.75 to 0.97 in men; 0.77 to 0.95 in women). The older groups displayed good coefficients of variation (4.2% to 10.8% in men and 3.4% to 9.5% in women), but the intraclass correlations were low-to-high (0.43 to 0.84 in men; 0.42 to 0.93 in women). Overall, intra-session reliability was higher than inter-session reliability. Peak power was by far the most consistent variable, whereas flight and jump height had the most marked variability. The minimum detectable change varied from 10.5% to 33%, depending on the variable examined, suggesting important implications for intervention studies.     

Recreational exercise participation and aerobic fitness in men and women: Analysis of data from a national survey

We compared the relationship between predicted VO₂ max (ml kg^‐1min^‐1) and recreational exercise patterns, using secondary data analysis of a comprehensive national survey (18,293 subjects aged 15–69 years). Exercise participation and predicted VO₂ max data were available for about 50% of this sample (4933 females, 4738 males). As expected, VO₂ max was significantly lower in the females than in the males at any age (P < 0.0001). Age was the most significant predictor of VO₂ max (r = ‐0.71 for males, r = ‐0.73 for females). Adjusting the data for the body mass index (BMI) increased this relationship only slightly in the males (R — 0.75) and females (R = 0.79). The simultaneous inclusion of exercise participation data (intensity, duration, energy expenditure) did not increase the predictions meaningfully (R = 0.78 for the males, R = 0.81 for the females). These exercise participation parameters concomitantly accounted for only a very slight amount of the variance of VO₂ max in both the females (3.0%) and males (4.5%). To minimize the effects of age, the data were analysed using 5‐year intervals. Again, the exercise participation parameters accounted for only a small part of the variance in VO₂ max (< 10%), except in the 15‐ to 19‐year‐old males (24%). These data suggest that VO₂ max is not associated with participation in recreational exercise.     

Changes in leg strength 8 and 32 h after endurance exercise

The aim of this study was to determine the effects of a single bout of endurance exercise on subsequent strength performance. Eight males with a long history of resistance training performed isokinetic, isometric and isotonic leg extension strength tests 8 and 32 h after 50 min of cycle ergometry at 70-110% of critical power. The participants also completed a control condition in which no cycling was performed. Plasma lactate and ammonia were measured before and immediately after each strength test. Isokinetic, isometric and isotonic leg extension torques were not significantly different 8 or 32 h after endurance exercise compared with the control condition ( P > 0.05). A large (50.3%), but not statistically significant, increase in plasma ammonia was evident during the strength tests performed 8 h after endurance exercise, while a significant ( P ? 0.05) increase in ammonia was also seen 32 h after endurance exercise. No significant changes in plasma ammonia were evident in the control condition. Our results suggest that leg extension strength was not compromised by an earlier bout of endurance cycling. However, metabolic activity during the strength tests might have been altered by the preceding bout of endurance exercise.     

Changes in leg strength 8 and 32 h after endurance exercise

The aim of this study was to determine the effects of a single bout of endurance exercise on subsequent strength performance. Eight males with a long history of resistance training performed isokinetic, isometric and isotonic leg extension strength tests 8 and 32 h after 50 min of cycle ergometry at 70-110% of critical power. The participants also completed a control condition in which no cycling was performed. Plasma lactate and ammonia were measured before and immediately after each strength test. Isokinetic, isometric and isotonic leg extension torques were not significantly different 8 or 32 h after endurance exercise compared with the control condition (P > 0.05). A large (50.3%), but not statistically significant, increase in plasma ammonia was evident during the strength tests performed 8 h after endurance exercise, while a significant (P < 0.05) increase in ammonia was also seen 32 h after endurance exercise. No significant changes in plasma ammonia were evident in the control condition. Our results suggest that leg extension strength was not compromised by an earlier bout of endurance cycling. However, metabolic activity during the strength tests might have been altered by the preceding bout of endurance exercise.     

Maximal strength and cortisol responses to psyching-up during the squat exercise

We studied the effect of psyching-up on one-repetition maximum (1-RM) performance and salivary cortisol responses during the squat exercise. Ten men (age 21.6?±?1.4 years; mean?±?s) and ten women (age 22.4?±?2.8 years) with weight training experience of 4.5?±?2.0 years participated in this study. One-repetition maximum squats were performed on a Smith machine during each of two different intervention conditions that were counterbalanced and consisted of a free choice psych-up and a cognitive distraction. Saliva samples were obtained at the beginning of each test session and immediately after the final 1-RM attempt. No significant difference in 1-RM was identified between psyching-up (104?±?50?kg) and cognitive distraction (106?±?52?kg). Performing a 1-RM in the squat exercise significantly increased salivary cortisol concentrations during both conditions (P <?0.05). There was no significant difference in salivary cortisol responses between conditions. These results suggest that psyching-up does not increase 1-RM performance during the squat exercise in strength-trained individuals.     

Maximal strength and cortisol responses to psyching-up during the squat exercise

We studied the effect of psyching-up on one-repetition maximum (1-RM) performance and salivary cortisol responses during the squat exercise. Ten men (age 21.6+/-1.4 years; mean+/-s) and ten women (age 22.4+/-2.8 years) with weight training experience of 4.5+/-2.0 years participated in this study. One-repetition maximum squats were performed on a Smith machine during each of two different intervention conditions that were counterbalanced and consisted of a free choice psych-up and a cognitive distraction. Saliva samples were obtained at the beginning of each test session and immediately after the final 1-RM attempt. No significant difference in 1-RM was identified between psyching-up (104+/-50 kg) and cognitive distraction (106+/-52 kg). Performing a 1-RM in the squat exercise significantly increased salivary cortisol concentrations during both conditions (P<0.05). There was no significant difference in salivary cortisol responses between conditions. These results suggest that psyching-up does not increase 1-RM performance during the squat exercise in strength-trained individuals.     

Bilateral practice improves dominant leg performance in long jump

Benefits of bilateral practice both for the non-dominant and for the dominant body side have been shown in several studies. Thereby, most of the studies included movement tasks of the upper extremity or investigated sports games in which the ability of acting bilaterally is an essential basis for success and, thus, a bilateral practice is reasonable anyway. Individual unilaterally performed sports including movement tasks of the lower extremity are rarely investigated. Therefore, the aim of our study was to test if contralateral transfer due to bilateral practice can be found in an unilaterally performed sport including the lower extremity. We trained and tested 61 adolescent athletes in long jump to compare the jumping performance of the dominant leg after a 12-week practice period between two groups: a bilateral practice group that practiced specific long jump exercises with both the dominant and non-dominant leg and an unilateral practice group that practiced specific long jump exercises only with the dominant leg. Results showed a superior effect of bilateral practice compared to unilateral practice regarding the jumping performance of the dominant leg. The performance increase at post-test and retention-test for the dominant limb was significantly higher for the bilateral practice group (pre-to-post: 5.2%, pre-to-retention: 7.4%) compared to the unilateral practice group (pre-to-post: 3.4%, pre-to-retention: 4.5%). Thus, bilateral practice should be established in the early practice programmes of track and field athletes to improve the performance of the dominant take-off leg.     

Explaining long-term exercise adherence in women who complete a structured exercise program

The purpose of this study was to qualitatively examine factors related to physical activity adherence to understand why women continue to participate in long-term exercise after completing a structured exercise program. Data were collected from focus groups, interviews, and e-mails, and analysis used grounded theory. The central category related to physical activity adherence was self-worth. Motivation, activity enjoyment, priorities, body image, ability to access support, and self-regulation skills had an impact on the self-worth of nonadherers and adherers. Women must value themselves enough to continue to participate in physical activity once they start. Exercise and fitness professionals are encouraged to use strategies to increase self-worth and long-term adherence to physical activity. Some recommended strategies include (a) increasing motivation and enjoyment relative to activity, (b) making activity a high priority in a woman's life, (c) improving or deemphasizing body image, (d) increasing a woman's ability to access support, and (e) facilitating the use of self-regulation strategies. This study is the first to examine qualitative perspectives of exercise adherence among women who completed a structured exercise program. Several concepts related to adherence presented in the quantitative literature are confirmed and enhanced in this study.     

Resistance training promotes increase in intracellular hydration in men and women

Abstract

The main purpose of the present study was to investigate the effect of 16 weeks of resistance training (RT) on body water in men and women. Thirty men (22.7 ± 4.4 years, 68.4 ± 9.0 kg and 174.5 ± 6.6 cm) and 34 women (22.7 ± 4.1 years, 58.8 ± 11.9 kg and 162.6 ± 6.2 cm) underwent progressive RT for 16 weeks (2 phases, 8 weeks each), 3 times per week, that consisted of 10–12 whole body exercises with 3 sets of 8–12 repetitions maximum. Total body water, TBW (intracellular water, ICW and extracellular water, ECW compartments) and skeletal muscle mass (SMM) were assessed using a spectral bioelectrical impedance device (Xitron 4200 Bioimpedance Spectrum Analyzer). TBW, ICW compartment and SMM increased significantly (P < 0.05) over time in men (+7.5%, +8.2% and +4.2%, respectively) and women (+7.6%, +11.0% +3.9%, respectively), with no sex by time interaction (P > 0.05). We conclude that progressive RT promotes an increase in body water, principally by intracellular content; however, the hydration status is not influenced by sex.     

河南省职业女性心理健康状况与体育锻炼的调查研究

选用中国社会科学院心理研究所研制发行WJZ心理测验与统计软件系统中<心理健康测查量表(PHI)>对河南省11种职业女性进行心理健康测试,并对其体育锻炼现状进行调查分析.结果显示:职业女性心理健康状况基本呈正态性分布,但各因子检出率比较高,心理健康状况与其年龄、文化程度无关,与其职称和参与体育锻炼状况相关显著,找出影响职业女性参与体育锻炼的主要因素,并提出了相应的对策与建议.     

Quantifying ice hockey goaltender leg pad kinematics and the effect that different leg pad styles have on performance

Goaltender leg pad innovations, whether the result of professional player feedback or National Hockey League equipment regulations, are rarely tested for their effects on the goaltender’s body. This study quantified peak drop velocity and range of motion of four different ice hockey goalie leg pads with respect to the goaltenders’ legs during butterfly manoeuvres. Twelve junior goaltenders, ranging from 16 to 20 years of age, performed five butterfly manoeuvres in each of the four leg pad conditions (flexible-tight leg channel, flexible-wide leg channel, stiff-wide leg channel and control). The pad conditions followed similar kinematic patterns in the sagittal and frontal planes. In the transverse plane, the stiff-wide pad achieved significantly greater external rotation (~10°) during the butterfly compared to the flex-tight and the flex-wide leg pad conditions. Goaltenders performed significantly faster butterflies in the flex-tight (3.05 m/s) and the flex-wide (3.0 m/s) leg pad conditions compared to their own control (2.82 m/s) leg pads (P = 0.018 and P = 0.004, respectively). The kinematic information obtained during this study provides ice hockey goaltender equipment manufacturers with a baseline understanding of how leg pads move with respect to the goaltender’s legs. Future leg pad modifications can then be compared to these data to understand the modification’s effect on the goaltender’s body and performance ensuring that leg pads continue to improve both the safety and performance of goaltenders.     

Static and dynamic single leg postural control performance during dual-task paradigms

Combining dynamic postural control assessments and cognitive tasks may give clinicians a more accurate indication of postural control under sport-like conditions compared to single-task assessments. We examined postural control, cognitive and squatting performance of healthy individuals during static and dynamic postural control assessments in single- and dual-task paradigms. Thirty participants (female = 22, male = 8; age = 20.8 ± 1.6 years, height = 157.9 ± 13.0 cm, mass = 67.8 ± 20.6 kg) completed single-leg stance and single-leg squat assessments on a force plate individually (single-task) and concurrently (dual-task) with two cognitive assessments, a modified Stroop test and the Brooks Spatial Memory Test. Outcomes included centre of pressure speed, 95% confidence ellipse, squat depth and speed and cognitive test measures (percentage of correct answers and reaction time). Postural control performance varied between postural control assessments and testing paradigms. Participants did not squat as deep and squatted slower (P < 0.001) during dual-task paradigms (≤12.69 ± 3.4 cm squat depth, ≤16.20 ± 4.6 cm · s^?1 squat speed) compared to single-task paradigms (14.57 ± 3.6 cm squat depth, 19.65 ± 5.5 cm · s^?1 squat speed). The percentage of correct answers did not change across testing conditions, but Stroop reaction time (725.81 ± 59.2 ms; F_2,58 = 7.725, P = 0.001) was slowest during single-leg squats compared to baseline (691.64 ± 80.1 ms; P = 0.038) and single-task paradigms (681.33 ± 51.5 ms; P < 0.001). Dynamic dual-task assessments may be more challenging to the postural control system and may better represent postural control performance during dynamic activities.     

Longitudinal examination of the exercise and self-esteem model in middle-aged women

This 2-year prospective study examined the exercise and self-esteem model in middle-aged women (N = 143) previously enrolled in a randomized controlled exercise trial. Across the 2-year period, increases in physical activity (PA) and self-efficacy and reductions in body mass index (BMI) were associated with improved subdomain self-perceptions relative to physical condition, and reductions in BMI were associated with improved subdomain self-perceptions relative to physical condition and body attractiveness. The effects of PA, self-efficacy, and BMI on changes in physical self-worth and global self-esteem were mediated by changes in self-perceptions relative to physical condition and body attractiveness. The results of this longitudinal analysis support the hierarchical and multidimensional structure of self-esteem and indicate that middle-aged women can enhance how they perceive their condition and body attractiveness by continued participation in physical activity, increasing their self-efficacy, and maintaining healthy BMI levels.