This study examined alterations in skeletal-muscle growth and atrophy-related molecular events after a single bout of moderate-intensity endurance exercise. Muscle biopsies were obtained from 10 men (23 ± 1 yr, body mass 80 ± 2 kg, and VO2peak 45 ± 1 ml · kg−1 · min−1) immediately (0 hr) and 3 hr after a 60-min bout of cycle exercise (60% ± 5% VO2peak). Corresponding muscle biopsies were also obtained under resting conditions. The phosphorylation status of insulin/IGF-PI3K molecular-signaling proteins, ubiquitin-proteasome-related gene expression, FOXO transcription factors, and myogenic regulatory factors in muscle samples was analyzed using multiplex analysis, Western blotting, and quantitative real-time polymerase chain reaction (qRT-PCR). A condition–time interaction was observed for Akt phosphorylation (p < .05) with multiplexing. Regardless of endurance exercise, Akt phosphorylation decreased and ERK phosphorylation increased at 3 hr compared with 0 hr (p < .05). Levels of p70S6K phosphorylation were 110% greater (p < .05) at 3 hr than at 0 hr using Western blots. MuRF mRNA expression postexercise increased; levels were 4.7- and 5.7-fold greater (p < .05) at 0 hr and 3 hr, respectively, than at rest with qRT-PCR. Atrogin mRNA expression was up-regulated 3.2-fold 3 hr postexercise compared with rest. These findings demonstrate modest changes in the molecular responses to moderate endurance exercise in the absence of nutrition. This study provides the groundwork for future investigations designed to optimize the metabolic conditions necessary to positively influence the cellular mechanisms specific to skeletal-muscle protein turnover during recovery from endurance exercise.
Stefan M. Pasiakos, Holly L. McClung, James P. McClung, Maria L. Urso, Matthew A. Pikosky, Gregory J. Cloutier, Roger A. Fielding and Andrew J. Young
Erik J. Groessl, Robert M. Kaplan, Steven N. Blair, W. Jack Rejeski, Jeffrey A. Katula, Abby C. King, Roger A. Fielding, Nancy W. Glynn and Marco Pahor
We examined the costs of a physical activity (PA) and an educational comparison intervention. 424 older adults at risk for mobility disability were randomly assigned to either condition. The PA program consisted of center-based exercise sessions 3× weekly for 8 weeks, 2× weekly for weeks 9 to 24 and weekly behavioral counseling for 10 weeks. Optional sessions were offered during maintenance weeks (25−52). The comparison intervention consisted of weekly education meetings for 24 weeks, and then monthly for 6 months. Cost analyses were conducted from the “payer’s” perspective, with a 1-year time horizon. Intervention costs were estimated by tracking personnel activities and materials used for each intervention and multiplying by national unit cost averages. The average cost/participant was $1134 and $175 for the PA and the comparison interventions, respectively. A preliminary cost/effectiveness analysis gauged the cost/disability avoided to be $28,206. Costs for this PA program for older adults are comparable to those of other PA interventions. The results are preliminary and a longer study is required to fully assess the costs and health benefits of these interventions.
Edward M. Phillips, Jeffrey Katula, Michael E. Miller, Michael P. Walkup, Jennifer S. Brach, Abby C. King, W. Jack Rejeski, Tim Church and Roger A. Fielding
To examine baseline characteristics and change in gait speed and Short Physical Performance Battery (SPPB) scores in participants medically suspended (MS) from a physical activity intervention (PA).
Randomized controlled trial.
University and community centers.
Sedentary older adults (N = 213) randomized to PA in the Lifestyle Interventions and Independence for Elders Pilot (LIFE-P).
MS was defined as missing 3 consecutive PA sessions in adoption and transition phases or 2 wk in maintenance phase because of a health event.
In all, 122 participants completed PA without MS (NMS subgroup), 48 participants underwent MS and resumed PA (SR subgroup), and 43 participants underwent MS and did not complete PA (SNR subgroup). At baseline, SNR walked slower (p = .03), took more prescribed medications (p = .02), and had lower SPPB scores than NMS and SR (p = .02). Changes from baseline to Month 12 SPPB scores were affected by suspension status, adjusted mean (SE) SPPB change: SNR 0.0957 (0.3184), SR 0.9413 (0.3063), NMS 1.0720 (0.1871); p = .03.
MS participants unable to return to complete the PA in a trial of mobility-limited sedentary older adults had slower walking speeds, lower SPPB scores, and a higher number of prescribed medications at baseline. Change in SPPB scores at 12 months was related to suspension status.
Michael P. Corcoran, Miriam E. Nelson, Jennifer M. Sacheck, Kieran F. Reid, Dylan Kirn, Roger A. Fielding, Kenneth K.H. Chui and Sara C. Folta
This cluster-randomized trial was designed to determine the efficacy of a 6-month exercise-nutritional supplement program (ENP) on physical function and nutritional status for older adults and the feasibility of implementing this program in a senior living setting. Twenty senior-living facilities were randomized to either a 3 day per week group-based ENP led by a trained facility staff member or a health education program (SAP). Participants (N = 121) completed a short physical performance battery, 400-m walk, handgrip strength test, and mini-nutrition assessment. 25-hydroxyvitamin D [25(OH)D], insulin-like growth-factor 1 (IGF-1), and activity level were also measured. The ENP did not significantly improve physical function or nutritional status compared with the SAP. Compared with baseline, participants in the ENP engaged in 39 min less physical activity per week at 6 months. Several facility characteristics hindered implementation of the ENP. This study highlights the complexity of implementing an evidence-based program in a field setting.