Flywheel or free weight training for improvement of lower limbs strength?

BACKROUND: New training methods are constantly used to improve the ability of skeletal muscles to develop strength. OBJECTIVE: The aim of the present study was to investigate the effect of half-squat training with free weights and flywheel device on isokinetic knee muscle strength for well-trained amateur soccer players. METHODS: Forty eight players were randomly divided into three groups (n= 16 each): Desmotech Training group (DT), Free Weight Training group (WT) and one Control Group (CON). DT and WT performed an eight-week half-squat training program, with two sessions per week. The DT group performed training with a flywheel device. Isokinetic concentric-eccentric strength assessments of the knee extensors-flexors muscle groups were performed at different angular velocities (60, 180 and 240∘/s). RESULTS: The eight-week training program improved all the isokinetic joint moment indicators examined in the DT and WT groups (p< 0.01). The DT group achieved higher performances at all the isokinetic parameters examined, however, without statistically significant differences to the WT group. CONCLUSIONS: Flywheel-based exercise is an effective training method and is suggested to be used to strengthen the lower limbs of soccer players.

Oxygen Delivery and Muscle Deoxygenation during Continuous, Long- and Short-Interval Exercise.

This study compared the O2 delivery (a central determinant of VO2) and muscle deoxygenation (reflecting a peripheral determinant of VO2) during intense continuous, long-interval, and short-interval exercise protocols. Twelve young men completed the 3 protocols with equal overall effort. Simultaneous and continuous recordings of central hemodynamics, muscle oxygenation/deoxygenation and VO2 were performed. Peak responses for stroke volume and peripheral resistance did not differ among protocols, whereas peak cardiac output and VO2 were higher in long-interval vs. continuous and short-interval protocols with inactive rest phases (p<0.05). The average responses for all central parameters were higher in continuous and long-interval vs. short-interval exercise (p<0.05); average VO2 and exercise-time above 80% VO2max were also higher in continuous and long-interval vs. short-interval protocol (p<0.05). Muscle de-oxygenation (↑Δdeoxyhemoglobin,↓Δoxyhemoglobin, ↓muscle O2-saturation), as well as the mismatch of O2 delivery and utilization (Δdeoxyhemoglobin/VO2) were remarkably alike among protocols. In conclusion, all 3 protocols resulted in a great activation of central and peripheral determinants of VO2. When performed with equal overall effort, the intense continuous and interval modalities reveal similarities in muscle O2-utilization response, but differences in central hemodynamic and VO2 responses. Intense continuous and long-interval protocols exert a more commanding role on the cardiovascular system and VO2 response compared to short-interval exercise with inactive rest phases.

Training, detraining, and retraining effects on glycemic control and physical fitness in women with type 2 diabetes.

Little is known about the detraining and retraining effects of exercise in patients with diabetes. The purpose of the present study was to investigate the effects of training, detraining, and retraining, using a combined strength and aerobic exercise program on glycemic control in women with type 2 diabetes. Thirteen postmenopausal women with type 2 diabetes (n = 13, age: 55.8 ± 5.1 years) followed a supervised aerobic and strength training program for 9 months, which was interrupted for 3 months (detraining) and resumed again for a period of 9 months (retraining). Anthropometric characteristics, glycemic control, and physical fitness were determined at baseline and after 9, 12, and 21 months. Training induced a small reduction in body mass index (BMI: -3.3%, 95% CI -5.1 to -1.5%), a moderate decrease in fasting plasma glucose (FPG: -12.0%, 95% CI -20.70 to -3.2%), glycosylated hemoglobin (HbA1c: -4.7%, 95% CI -12.1 to 2.7%), and a large decrease in postprandial glucose (PPG: - 12.1%, 95% CI -20.2 to -4.1%). In addition, there was an increase in power output (20.2%, 95% CI 6.9 to 33.6%) and total muscle strength (33.8%, 95% CI 21.4 to 46.1%). Detraining reversed PPG, HbA1c, and physical fitness. Resumption of training, however, led to a moderate decrease in BMI (-5.4%, 95% CI -8.1 to -2.7%), PPG (-9.5%, 95% CI -19.4 to 0.3%), and HbA1c (-6.8%, 95% CI -14.1 to 0.5%), and to large changes in FPG (-20.9%, 95% CI -31.9 to -9.9%), power output (33.1%, 95% CI 17.9 to 48.4%) and total muscle strength (48.2%, 95% CI 34.0 to 62.4%) compared to baseline. Thus, systematic training improves body composition, glycemic control and physical fitness in patients with type 2 diabetes. The cessation of exercise brings about negative alterations, while retraining restores all beneficial adaptations and improves them even more. Therefore, diabetic patients should follow a regular and an uninterrupted exercise program throughout life in order to control glucose metabolism and improve health.

Hormonal responses after a strength endurance resistance exercise protocol in young and elderly males.

This study examined testosterone, cortisol and growth hormone responses in elderly and young men after a strength endurance protocol. Eight elderly (age: 69 +/- 5 yrs) and nine young (age: 23 +/- 1 yrs) males with recreational experience in resistance training performed a strength endurance protocol, which included six exercises. At each exercise, the subjects performed 3 sets of 15 reps at 60 % of 1-RM with a 90 s rest interval between sets. The subjects also participated in a control session. Hormonal and blood lactate concentrations were measured before exercise, immediately after exercise and 15 min after the end of exercise. Blood lactate increased (p<0.05) with resistance exercise in both age groups with the highest increases observed in the young males. Testosterone and cortisol concentrations were higher (p<0.05) immediately and 15 min after exercise as compared to the respective control session values in both young and elderly subjects, whereas no differences were observed between groups (p>0.05). Growth hormone concentration increased (p<0.05) after resistance exercise compared to the control session in both age groups. This increase was higher (p<0.05) in the young as compared to the elderly group. The above results show that a moderate intensity - high repetition resistance exercise protocol for the improvement of strength endurance, seems to be a sufficient stimulus that increases testosterone, growth hormone and cortisol concentrations in elderly males. These hormonal responses may create an optimal metabolic environment, which improves muscular function after a strength endurance program although the elderly subjects present an attenuated growth hormone response compared to younger ones.

Resistance training in older women: effect on vertical jump and functional performance.

AIM: Few studies have determined the effects of a heavy resistance training on vertical jump performance in older adults. The purpose of the present study was to evaluate the effects of a 12 week heavy resistance training in vertical jump and functional performance in healthy, inactive, older women. METHODS: Seventeen sedentary older women (aged 53-69 years) were assigned either to a control (C, n=8), or to a heavy resistance training (RT, n=9). The RT group trained knee extensors and flexors at 80% of 1-repetition maximum (1-RM), 3 days per week for 12 weeks. Both groups were evaluated in 1-RM lower body strength, squat jump (SJ) and countermovement jump (CMJ) height, and chair rising time, before and after the training period. RESULTS: After the training period, RT significantly improved (P<0.001) the 1-RM lower body strength, SJ, CMJ height, and chair rising by 68.9%, 24.5%, 21.7%, and 13%, respectively. Significant correlations were observed among the percent (%) change in 1-RM lower body strength and SJ (r=0.849, P<0.001), CMJ height (r=0.797, P<0.001), and chair rising time (r=-0.917, P<0.001). CONCLUSIONS: Muscle power improved after a short-term heavy resistance training, as measured by vertical jump and chair rising performance, in inactive older adults. The gains in muscle strength may contribute to the gains in chair rising time, SJ and CMJ height.

Serum leptin responses after acute resistance exercise protocols.

This study examined the acute effects of maximum strength (MS), muscular hypertrophy (MH), and strength endurance (SE) resistance exercise protocols on serum leptin. Ten young lean men (age = 23 +/- 4 yr; body weight = 79.6 +/- 5.2 kg; body fat = 10.2 +/- 3.9%) participated in MS [4 sets x 5 repetitions (reps) at 88% of 1 repetition maximum (1 RM) with 3 min of rest between sets], MH (4 sets x 10 reps at 75% of 1 RM with 2 min of rest between sets), SE (4 sets x 15 reps at 60% of 1 RM with 1 min of rest between sets), and control (C) sessions. Blood samples were collected before and immediately after exercise and after 30 min of recovery. Serum leptin at 30 min of recovery exhibited similar reductions from baseline after the MS (-20 +/- 5%), MH (-20 +/- 4%), and SE (-15 +/- 6%) protocols that were comparable to fasting-induced reduction in the C session (-12 +/- 3%) (P < 0.05). Furthermore, no differences were found in serum leptin among the MS, MH, SE, and C sessions immediately after exercise and at 30 min of recovery (P > 0.05). Cortisol was higher (P < 0.05) after the MH and SE protocols than after the MS and C sessions. Glucose and growth hormone were higher (P < 0.05) after exercise in the MS, MH, and SE protocols than after the C session. In conclusion, typical resistance exercise protocols designed for development of MS, MH, and SE did not result in serum leptin changes when sampled immediately or 30 min postexercise.