1.
Muscle protein breakdown is impaired during immobilization compared to during a subsequent retraining period in older men: no effect of anti-inflammatory medication.
Dideriksen, K, Reitelseder, S, Agergaard, J, Boesen, AP, Aas, SN, Raastad, T, Holm, L
Pflugers Archiv : European journal of physiology. 2020;(2):281-292
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Abstract
Muscle inactivity reduces muscle protein synthesis (MPS), whereas a subsequent period of rehabilitation resistance training (retraining) increases MPS. However, less is known regarding muscle protein breakdown (MPB) during such conditions. Furthermore, nonsteroidal anti-inflammatory drugs (NSAIDs) may have a dampening effect on MPB during periods of inactivity in older individuals. Thus, we measured the average MPB, by use of the deuterated water methodology, during an immobilization period and a subsequent retraining period in older individuals with and without NSAID treatment. Eighteen men (60-80 years: range) were randomly assigned to ibuprofen (1200 mg/d, Ibu) or placebo (Plc). One lower limb was immobilized in a cast for 2 weeks and retrained for 2 weeks, and 2 × 20 g of whey protein was ingested daily during both periods. Besides MPB, the protein expression of different muscle degradation signaling molecules was investigated. MPB was lower during immobilization compared to retraining (p < 0.01). NSAID treatment did not affect the MPB rate during immobilization or retraining (p > 0.05). The protein expression of muscle degradation signaling molecules changed during the study intervention but were unaffected by NSAID treatment. The finding that MPB was lower during immobilization than during retraining indicates that an increased MPB may play an important role in the muscle protein remodeling processes taking place within the initial retraining period. Moreover, NSAID treatment did not significantly influence the MPB rate during 2 weeks of lower limb immobilization or during 2 weeks of subsequent retraining in older individuals.
2.
Dairy Protein Supplementation Modulates the Human Skeletal Muscle microRNA Response to Lower Limb Immobilization.
D'Souza, RF, Zeng, N, Figueiredo, VC, Markworth, JF, Durainayagam, BR, Mitchell, SM, Fanning, AC, Poppitt, SD, Cameron-Smith, D, Mitchell, CJ
Molecular nutrition & food research. 2018;(7):e1701028
Abstract
Limb immobilization results in a rapid loss of muscle size and strength. The resultant alterations in signaling pathways governing myogenesis, catabolism, and mitochondrial biogenesis are likely to include posttranscriptional regulation mediated by altered microRNAs (miRNAs). Given that protein ingestion exerts an anabolic action and may act as a countermeasure to mitigate muscle loss with immobilization, it is important to examine miRNA in this context. The objective of the study is therefore to characterize the vastus lateralis miRNA response to 14 days of disuse in males (45-60 years) randomized to receive supplementation with 20 g d-1 of dairy protein (n = 12) or isocaloric carbohydrate placebo (n = 13). Biopsies are collected before and after a 2-week immobilization period. Of the 24 miRNAs previously identified in myogenic regulation, seven (miR-133a, -206, -15a, -451a, -126, -208b, and let-7e) are increased with immobilization irrespective of group; five (miR-16, -494, let-7a, -7c, and 7d) increased only in the carbohydrate group; and eight (miR-1, -486, -23a, -23b, -26a, -148b, let-7b, and -7g) are divergently expressed between groups (suppressed with protein). The ability of protein supplementation to differentially regulate miRNAs involved in key muscle regulatory pathways following short-term limb immobilization reflects potential protective function in mitigating muscle loss during limb immobilization.
3.
Neuromuscular electrical stimulation prevents muscle disuse atrophy during leg immobilization in humans.
Dirks, ML, Wall, BT, Snijders, T, Ottenbros, CL, Verdijk, LB, van Loon, LJ
Acta physiologica (Oxford, England). 2014;(3):628-41
Abstract
AIM: Short periods of muscle disuse, due to illness or injury, result in substantial skeletal muscle atrophy. Recently, we have shown that a single session of neuromuscular electrical stimulation (NMES) increases muscle protein synthesis rates. The aim was to investigate the capacity for daily NMES to attenuate muscle atrophy during short-term muscle disuse. METHODS Twenty-four healthy, young (23 ± 1 year) males participated in the present study. Volunteers were subjected to 5 days of one-legged knee immobilization with (NMES; n = 12) or without (CON; n = 12) supervised NMES sessions (40-min sessions, twice daily). Two days prior to and immediately after the immobilization period, CT scans and single-leg one-repetition maximum (1RM) strength tests were performed to assess quadriceps muscle cross-sectional area (CSA) and leg muscle strength respectively. Furthermore, muscle biopsies were taken to assess muscle fibre CSA, satellite cell content and mRNA and protein expression of selected genes. RESULTS In CON, immobilization reduced quadriceps CSA by 3.5 ± 0.5% (P < 0.0001) and muscle strength by 9 ± 2% (P < 0.05). In contrast, no significant muscle loss was detected following immobilization in NMES although strength declined by 7 ± 3% (P < 0.05). Muscle MAFbx and MuRF1 mRNA expression increased following immobilization in CON (P < 0.001 and P = 0.07 respectively), whereas levels either declined (P < 0.01) or did not change in NMES, respectively. Immobilization led to an increase in muscle myostatin mRNA expression in CON (P < 0.05), but remained unchanged in NMES. CONCLUSION During short-term disuse, NMES represents an effective interventional strategy to prevent the loss of muscle mass, but it does not allow preservation of muscle strength. NMES during disuse may be of important clinical relevance in both health and disease.
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Effects of traditional swaddling on development: a randomized controlled trial.
Manaseki-Holland, S, Spier, E, Bavuusuren, B, Bayandorj, T, Sprachman, S, Marshall, T
Pediatrics. 2010;(6):e1485-92
Abstract
OBJECTIVE Evidence of the effects of tight, prolonged binding of infants on development is inconclusive and based on small ethnographic studies. The null hypothesis was that Mongolian infants not swaddled or swaddled tightly in a traditional setting (to >7 months of age) do not have significantly different scores for the Bayley Scales of Infant Development, Second Edition (BSID-II). PATIENTS AND METHODS In a randomized controlled trial, 1279 healthy newborns in Ulaanbaatar, Mongolia, were allocated at birth to traditional swaddling or nonswaddling. The families received 7 months of home visits to collect data and monitor compliance. At 11 to 17 months of age, the BSID-II was administered to 1100 children. RESULTS No significant between-group differences were found in mean scaled mental and psychomotor developmental scores. The unadjusted mean difference between the groups was -0.69 (95% confidence interval [CI]: -2.59 to 1.19) for psychomotor and -0.42 (95% CI: -1.68 to 0.84) for mental scores in favor of the swaddling group. A subgroup analysis of the compliant sample produced similar results. BSID-II-scaled psychomotor and mental scores were 99.98 (95% CI: 99.03-100.92) and 105.52 (95% CI: 104.89-106.14), respectively. Background characteristics were balanced across the groups. CONCLUSIONS In the Mongolian context, prolonged swaddling in the first year of life did not have any significant impact on children's early mental or psychomotor development. Additional studies in other settings need to confirm this finding. The Mongolian infants in this trial had scaled BSID-II mental and psychomotor scores comparable to United States norms.