Protein ingestion preserves proteasome activity during intense aseptic inflammation and facilitates skeletal muscle recovery in humans

Abstract

The ubiquitin-proteasome system (UPS) is the main cellular proteolytic system responsible for the degradation of normal and abnormal (e.g. oxidised) proteins. Under catabolic conditions characterised by chronic inflammation, the UPS is activated resulting in proteolysis, muscle wasting and impaired muscle function. Milk proteins provide sulphur-containing amino acid and have been proposed to affect muscle inflammation. However, the response of the UPS to aseptic inflammation and protein supplementation is largely unknown. The aim of this study was to investigate how milk protein supplementation affects UPS activity and skeletal muscle function under conditions of aseptic injury induced by intense, eccentric exercise. In a double-blind, cross-over, repeated measures design, eleven men received either placebo (PLA) or milk protein concentrate (PRO, 4×20 g on exercise day and 20 g/d for the following 8 days), following an acute bout of eccentric exercise (twenty sets of fifteen eccentric contractions at 30°/s) on an isokinetic dynamometer. In each trial, muscle biopsies were obtained from the vastus lateralis muscle at baseline, as well as at 2 and 8 d post exercise, whereas blood samples were collected before exercise and at 6 h, 1 d, 2 d and 8 d post exercise. Muscle strength and soreness were assessed before exercise, 6 h post exercise and then daily for 8 consecutive days. PRO preserved chymotrypsin-like activity and attenuated the decrease of strength, facilitating its recovery. PRO also prevented the increase of NF-κB phosphorylation and HSP70 expression throughout recovery. We conclude that milk PRO supplementation following exercise-induced muscle trauma preserves proteasome activity and attenuates strength decline during the pro-inflammatory phase.

Post-Game High Protein Intake May Improve Recovery of Football-Specific Performance during a Congested Game Fixture: Results from the PRO-FOOTBALL Study

“…Protein supplementation may induce improved neuromuscular performance. There are numerous reports that various forms of protein supplementation (e.g., fast digestible soluble milk protein, milk protein concentrate, oat protein, and whey protein isolate) may prevent or attenuate skeletal muscle performance deterioration following an exercise damaging protocol or even increase skeletal muscle fatigue resistance [ 48 , 68 , 69 , 70 , 71 ]. These effects may be mediated by an upregulation of skeletal muscle carnosine content [ 72 ].…”

“…Participants in this study were provided with ~25–30 g and ~5 g of BCAAs on game and training days, respectively. BCAAs, particularly leucine, have been shown to provide a potent stimulus for enhanced ribosomic protein translation and attenuated proteolysis [ 48 , 49 ]. Moreover, BCAAs may be transaminated, under pro-inflammatory conditions, to glutamate, thereby enhancing glutamine synthesis, which is a substrate highly used by pro-inflammatory immune cells such as macrophages.…”

“…A preliminary power analysis (effect size > 0.55, probability error of 0.05, power of 0.90), indicated that a sample size of 16–18 subjects is necessary to detect a statistically meaningful treatment effect among serial measurements in response to repeated football games [ 9 , 48 ]. Consequently, 29 competitive male football players were initially approached/interviewed, but 20 participated in the study.…”

Disparate Habitual Physical Activity and Dietary Intake Profiles of Elderly Men with Low and Elevated Systemic Inflammation

“…Standing body mass and height were measured on a beam balance with stadiometer (Beam Balance-Stadiometer, SECA, Vogel & Halke, Hamburg, Germany) with participants wearing light clothing and no shoes as described previously [ 52 ]. Body composition [including fat mass, fat-free mass (FFM), percent of fat, lean body mass (LBM)] was assessed by dual emission X-ray absorptiometry (DXA, GE Healthcare, Lunar DPX NT, Diegem, Belgium) with participants in supine position as described before [ 53 ]. Appendicular lean mass (ALM) and skeletal muscle mass index (SMI) were calculated as the sum of muscle mass (kg) of the four limbs (based on DXA scan) and as ALM divided by height by meters squared (kg/m 2 ), respectively [ 49 ], while sarcopenia status was determined according to the criteria established by EWGSOP [ 49 ].…”

The redox-dependent regulation of satellite cells following aseptic muscle trauma (SpEED): Study protocol for a randomized controlled trial

“…Knee extensors will be isolated using straps in the shoulders, hips and thigh. This protocol has been described in the literature to effectively induce a significant level of skeletal muscle damage and myofibrillar disruption as documented with electron microscopy and immunohistochemistry [30,31].…”