Targeting anabolic impairment in response to resistance exercise in older adults with mobility impairments: potential mechanisms and rehabilitation approaches

pre-printMuscle atrophy is associated with healthy aging (i.e., sarcopenia) and may be compounded by comorbidities, injury, surgery, illness, and physical inactivity. While a bout of resistance exercise increases protein synthesis rates in healthy young skeletal muscle, the effectiveness of resistance exercise to mount a protein synthetic response is less pronounced in older adults. Improving anabolic sensitivity to resistance exercise, thereby enhancing physical function, is most critical in needy older adults with clinical conditions that render them "low responders". In this paper, we discuss potential mechanisms contributing to anabolic impairment to resistance exercise and highlight the need to improve anabolic responsiveness in low responders. This is followed with evidence suggesting that the recovery period of resistance exercise provides an opportunity to amplify the exercise-induced anabolic response using protein/essential amino acid ingestion. This anabolic strategy, if repeated chronically, may improve lean muscle gains, decrease time to recovery of function during periods of rehabilitation, and overall, maintain/improve physical independence and reduce mortality rates in older adults

The influence of controlled frequency breathing on blood lactate levels during graded front crawl stroke swimming

Controlled frequency breathing (CFB) is a training technique used by swimmers in an effort to limit oxygen availability to the body and stimulate anaerobic metabolism. During CFB, a swimmer restricts breathing to one breath every six, seven, or even eight strokes per breath. The purpose of this study was to determine tb.e influen\u3c;:e of CFB on blood lactate, heart rate, and stroke rate during front crawl stroke swimming. A maximal exertion test was used to determine peak swimming velocity. Based on this maximal test, five different workloads were used to compare CFB and normal breathing (NB). Subjects swam three-minute workloads at 55%,65%,75%, 85%, and 95% of maximal effort with two minutes rest between each workload. Blood lactate and heart rate were measured immediately after each workload and stroke rate was counted manually. Subjects were assigned to breathe normally (NB) or to restrict their breathing to one breath every eight strokes (CFB). Breathing conditions were randomly assigned. Multivariate analysis was used to compare the blood lactate, heart rate, and stroke rate between NB and CFB. Tukey\u27s post hoc test was used when F-values were significant (p\u3c0.05). Twenty-eight subjects (18 females, 10 males) completed the entire protocol. As expected there were significant main effects for the heart rate and blood lactate responses to increasing workloads (p\u3c0.01). However, CFB did not alter blood lactate levels when compared to NB. Interestingly, heart rate (p=0.014) was lower and stroke rate (p=0.011) was higher in the CFB condition when compared to N\u27B

The influence of controlled frequency breathing on blood lactate levels during graded front crawl stroke swimming

Controlled frequency breathing (CFB) is a training technique used by swimmers in an effort to limit oxygen availability to the body and stimulate anaerobic metabolism. During CFB, a swimmer restricts breathing to one breath every six, seven, or even eight strokes per breath. The purpose of this study was to determine tb.e influen\u3c;:e of CFB on blood lactate, heart rate, and stroke rate during front crawl stroke swimming. A maximal exertion test was used to determine peak swimming velocity. Based on this maximal test, five different workloads were used to compare CFB and normal breathing (NB). Subjects swam three-minute workloads at 55%,65%,75%, 85%, and 95% of maximal effort with two minutes rest between each workload. Blood lactate and heart rate were measured immediately after each workload and stroke rate was counted manually. Subjects were assigned to breathe normally (NB) or to restrict their breathing to one breath every eight strokes (CFB). Breathing conditions were randomly assigned. Multivariate analysis was used to compare the blood lactate, heart rate, and stroke rate between NB and CFB. Tukey\u27s post hoc test was used when F-values were significant (p\u3c0.05). Twenty-eight subjects (18 females, 10 males) completed the entire protocol. As expected there were significant main effects for the heart rate and blood lactate responses to increasing workloads (p\u3c0.01). However, CFB did not alter blood lactate levels when compared to NB. Interestingly, heart rate (p=0.014) was lower and stroke rate (p=0.011) was higher in the CFB condition when compared to N\u27B

PGC-1α-Targeted Therapeutic Approaches to Enhance Muscle Recovery in Aging

Impaired muscle recovery (size and strength) following a disuse period commonly occurs in older adults. Many of these individuals are not able to adequately exercise due to pain and logistic barriers. Thus, nutritional and pharmacological therapeutics, that are translatable, are needed to promote muscle recovery following disuse in older individuals. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) may be a suitable therapeutic target due to pleiotropic regulation of skeletal muscle. This review focuses on nutritional and pharmacological interventions that target PGC-1α and related Sirtuin 1 (SIRT1) and 5′ AMP-activated protein kinase (AMPKα) signaling in muscle and thus may be rapidly translated to prevent muscle disuse atrophy and promote recovery. In this review, we present several therapeutics that target PGC-1α in skeletal muscle such as leucine, β-hydroxy-β-methylbuyrate (HMB), arginine, resveratrol, metformin and combination therapies that may have future application to conditions of disuse and recovery in humans

Targeting Anabolic Impairment in Response to Resistance Exercise in Older Adults with Mobility Impairments: Potential Mechanisms and Rehabilitation Approaches

Muscle atrophy is associated with healthy aging (i.e., sarcopenia) and may be compounded by comorbidities, injury, surgery, illness, and physical inactivity. While a bout of resistance exercise increases protein synthesis rates in healthy young skeletal muscle, the effectiveness of resistance exercise to mount a protein synthetic response is less pronounced in older adults. Improving anabolic sensitivity to resistance exercise, thereby enhancing physical function, is most critical in needy older adults with clinical conditions that render them “low responders”. In this paper, we discuss potential mechanisms contributing to anabolic impairment to resistance exercise and highlight the need to improve anabolic responsiveness in low responders. This is followed with evidence suggesting that the recovery period of resistance exercise provides an opportunity to amplify the exercise-induced anabolic response using protein/essential amino acid ingestion. This anabolic strategy, if repeated chronically, may improve lean muscle gains, decrease time to recovery of function during periods of rehabilitation, and overall, maintain/improve physical independence and reduce mortality rates in older adults

Blood lactate and metabolic responses to controlled frequency breathing during graded swimming

Controlled frequency breathing (CFB) is a training technique used by swimmers in an effort to simulate high-intensity workloads by limiting oxygen availability to the body and stimulating anaerobic metabolism. During CFB, a swimmer voluntarily restricts breathing, which, theoretically, limits oxygen availability and stimulates anaerobic metabolism. The purpose of this study was to determine the influence of CFB on blood lactate and metabolic responses during graded increases in swimming intensity. A free swimming (FS) protocol was used to determine blood lactate and heart rate (HR) responses to CFB, while a tethered swimming (TS) protocol was used to determine blood lactate, HR, and ventilatory responses to CFB. The subjects swam four 3-minute trials at workloads of 55, 65, 75, and 85% of peak intensity during both protocols. A total of 46 competitive collegiate swimmers participated in the study. Thirty-four subjects (14 men and 20 women) completed the FS protocol, and 12 subjects (7 men and 5 women) completed the TS protocol. CFB reduced ventilation and VO2 (p \u3c 0.05) during the TS protocol and reduced HR (p \u3c 0.05) during the FS protocol when compared to normal breathing. However, CFB did not alter blood lactate concentrations for either protocol (p \u3e 0.05). Our findings demonstrate that although CFB does not alter the blood lactate response to graded increases in swimming intensity, it appears to reduce the ventilatory and HR responses to exercise. Thus, swim coaches can use CFB at moderate intensities to simulate high-intensity training but should consider adjusting HR training zones to reflect the reduction in HR associated with reduced ventilation

Metabolic and biomechanic changes during controlled frequency breathing swimming

Ss (N = 12) swam three-minute workloads at 55, 75, and 85% of maximal exertion for a tethered swimming protocol and 55-95% for a free swimming protocol with either normal breathing or breathing restricted to one breath per eight strokes. Restricted breathing did not alter lactate levels, but did reduce oxygen consumption. Heart and stroke rateS were higher during restricted breathing swimming. Implication. Restricted breathing training compromises the specificity of training effects and could alter biomechanical properties of stroking