ABSTRACT Introduction: As a means of combating age-related declines in muscular strength and powe... more ABSTRACT Introduction: As a means of combating age-related declines in muscular strength and power, training interventions using conventional high intensity resistance training, which involves both concentric and eccentric muscle actions performed against a constant external load, have been utilised and demonstrated to have significant positive effects on some aspects of performance and health. However, while typically very effective at increasing muscle mass and strength, this traditional mode of resistance training appears to be less effective at increasing muscle power generation during high-speed contractions, which is important for the older adult to maintain function. Therefore, the effectiveness of alternative strength and power training regimens require investigation. Objectives: To compare the effects of eccentrically-biased (EB) and conventional (CONV) resistance training on: muscle architecture, 1 repetition maximum (1RM), isometric strength, isokinetic force-velocity characteristics, functional capacity and pulse wave velocity (PWV) in older adults. Methods: Twenty-eight older adults participated in the study (mean ± S.D. age, 68 ± 5 years). Of these, 13 were allocated to a wait-list control, 10 of whom progressed to the training groups (CONV, n=12; EB, n=13). Training was twice a week for 16 weeks. EB involved three sets of 10 concentric lifts at 50% of 1RM with the eccentric portion of repetitions performed unilaterally, alternating between limbs with each repetition. CONV involved two sets of 10 repetitions at 75% of 1RM. Knee extensor strength was assessed across a range of velocities (0-360º.s-1) while functional capacity was assessed via a 6 metre fast walk (6MFWT), timed up and go (TUG), stair climb and descent power tests and vertical jump. Vastus lateralis and gastrocnemius medialis muscle architecture were assessed using ultrasonography. Results: Both the EB and CONV regimens improved 1RM (Δ23-35%, P<0.01). Compared to the control group, both training regimens improved 6MFWT (Δ5-7%, P<0.01) and concentric torque at 60°/s and 120°/s (Δ6-8%, P<0.05). Additionally, statistically significant improvements were either only evident, or superior in the EB group for: isometric strength (Δ7%, P<0.05), concentric torque at 240°/s and 360°/s (Δ6- 11%, P<0.05), vastus lateralis thickness (Δ5%, P<0.05) and stair climb performance (Δ5%, P<0.01). PWV, pennation angle and fascicle length remained unchanged in both training groups. Discussion: This study suggests that eccentrically-biased resistance training is a viable and potentially preferable alternative to conventional resistance training for older adults. Whilst improvements in one repetition maximum and functional capacity were similar for both training modalities, quadriceps thickness and torque at higher isokinetic velocities increased only after EB. While longer term studies are required, these findings suggest that EB may be particularly valuable for a population that is prone to sarcopenia and falls. Furthermore, whilst eccentric-only training is impractical in a real-world gym setting due to the consistent need for assistance from a spotter to aid with the lifting of the weights, this study has demonstrated that eccentrically-biased training can be successfully performed without assistance, using resistance training machines that are widely available. Conclusion: EB appears to be superior to CONV at increasing torque at high contraction velocities. This has important implications for the preservation of functional activities and falls prevention.
International journal of sports physiology and performance, 2009
Uncoupled cycling cranks are designed to remove the ability of one leg to assist the other during... more Uncoupled cycling cranks are designed to remove the ability of one leg to assist the other during the cycling action. It has been suggested that training with this type of crank can increase mechanical efficiency. However, whether these improvements can confer performance enhancement in already well-trained cyclists has not been reported. Fourteen well-trained cyclists (13 males, 1 female; 32.4 +/- 8.8 y; 74.5 +/- 10.3 kg; Vo2max 60.6 +/- 5.5 mL.kg-1.min-1; mean +/- SD) participated in this study. Participants were randomized to training on a stationary bicycle using either an uncoupled (n = 7) or traditional crank (n = 7) system. Training involved 1-h sessions, 3 days per week for 6 weeks, and at a heart rate equivalent to 70% of peak power output (PPO) substituted into the training schedule in place of other training. Vo2max, lactate threshold, gross efficiency, and cycling performance were measured before and following the training intervention. Pre- and posttesting was conducted...
ABSTRACT Introduction: As a means of combating age-related declines in muscular strength and powe... more ABSTRACT Introduction: As a means of combating age-related declines in muscular strength and power, training interventions using conventional high intensity resistance training, which involves both concentric and eccentric muscle actions performed against a constant external load, have been utilised and demonstrated to have significant positive effects on some aspects of performance and health. However, while typically very effective at increasing muscle mass and strength, this traditional mode of resistance training appears to be less effective at increasing muscle power generation during high-speed contractions, which is important for the older adult to maintain function. Therefore, the effectiveness of alternative strength and power training regimens require investigation. Objectives: To compare the effects of eccentrically-biased (EB) and conventional (CONV) resistance training on: muscle architecture, 1 repetition maximum (1RM), isometric strength, isokinetic force-velocity characteristics, functional capacity and pulse wave velocity (PWV) in older adults. Methods: Twenty-eight older adults participated in the study (mean ± S.D. age, 68 ± 5 years). Of these, 13 were allocated to a wait-list control, 10 of whom progressed to the training groups (CONV, n=12; EB, n=13). Training was twice a week for 16 weeks. EB involved three sets of 10 concentric lifts at 50% of 1RM with the eccentric portion of repetitions performed unilaterally, alternating between limbs with each repetition. CONV involved two sets of 10 repetitions at 75% of 1RM. Knee extensor strength was assessed across a range of velocities (0-360º.s-1) while functional capacity was assessed via a 6 metre fast walk (6MFWT), timed up and go (TUG), stair climb and descent power tests and vertical jump. Vastus lateralis and gastrocnemius medialis muscle architecture were assessed using ultrasonography. Results: Both the EB and CONV regimens improved 1RM (Δ23-35%, P<0.01). Compared to the control group, both training regimens improved 6MFWT (Δ5-7%, P<0.01) and concentric torque at 60°/s and 120°/s (Δ6-8%, P<0.05). Additionally, statistically significant improvements were either only evident, or superior in the EB group for: isometric strength (Δ7%, P<0.05), concentric torque at 240°/s and 360°/s (Δ6- 11%, P<0.05), vastus lateralis thickness (Δ5%, P<0.05) and stair climb performance (Δ5%, P<0.01). PWV, pennation angle and fascicle length remained unchanged in both training groups. Discussion: This study suggests that eccentrically-biased resistance training is a viable and potentially preferable alternative to conventional resistance training for older adults. Whilst improvements in one repetition maximum and functional capacity were similar for both training modalities, quadriceps thickness and torque at higher isokinetic velocities increased only after EB. While longer term studies are required, these findings suggest that EB may be particularly valuable for a population that is prone to sarcopenia and falls. Furthermore, whilst eccentric-only training is impractical in a real-world gym setting due to the consistent need for assistance from a spotter to aid with the lifting of the weights, this study has demonstrated that eccentrically-biased training can be successfully performed without assistance, using resistance training machines that are widely available. Conclusion: EB appears to be superior to CONV at increasing torque at high contraction velocities. This has important implications for the preservation of functional activities and falls prevention.
International journal of sports physiology and performance, 2009
Uncoupled cycling cranks are designed to remove the ability of one leg to assist the other during... more Uncoupled cycling cranks are designed to remove the ability of one leg to assist the other during the cycling action. It has been suggested that training with this type of crank can increase mechanical efficiency. However, whether these improvements can confer performance enhancement in already well-trained cyclists has not been reported. Fourteen well-trained cyclists (13 males, 1 female; 32.4 +/- 8.8 y; 74.5 +/- 10.3 kg; Vo2max 60.6 +/- 5.5 mL.kg-1.min-1; mean +/- SD) participated in this study. Participants were randomized to training on a stationary bicycle using either an uncoupled (n = 7) or traditional crank (n = 7) system. Training involved 1-h sessions, 3 days per week for 6 weeks, and at a heart rate equivalent to 70% of peak power output (PPO) substituted into the training schedule in place of other training. Vo2max, lactate threshold, gross efficiency, and cycling performance were measured before and following the training intervention. Pre- and posttesting was conducted...
Uploads
Papers by Isaac Raj