Recovery nutrition: timing and composition after endurance exercise

Alcalase-Assisted Mytilus edulis Hydrolysate: A Nutritional Approach for Recovery from Muscle Atrophy

Muscle atrophy is a complex physiological condition caused by a variety of reasons, including muscle disuse, aging, malnutrition, chronic diseases, immobilization, and hormonal imbalance. Beyond its effect on physical appearance, this condition significantly reduces the quality of human life, thus warranting the development of preventive strategies. Although exercising is effective in managing this condition, it is applicable only for individuals who can engage in physical activities and are not bedridden. A combination of exercise and nutritional supplementation has emerged as a more advantageous approach. Here, we evaluated the effects of enzyme-assisted hydrolysates of Mytilus edulis prepared using Protamex (PMH), Alcalase (AMH), or Flavourzyme (FMH) in protecting against muscle atrophy in a dexamethasone (Dex)-induced muscular atrophy model in vitro and in vitro. Alcalase-assisted M. edulis hydrolysate (AMH) was the most efficient among the tested treatments and resulted in higher protein recovery (57.06 ± 0.42%) and abundant amino acid composition (43,158 mg/100 g; 43.16%). AMH treatment also escalated the proliferation of C2C12 cells while increasing the total number of nuclei, myotube coverage, and myotube diameter. These results were corroborated by a successful reduction in the levels of proteins responsible for muscle atrophy, including E3 ubiquitin ligases, and an increase in the expression of proteins associated with muscle hypertrophy, including myogenin and MyHC. These results were further solidified by the successful enhancement of locomotor ability and body weight in zebrafish following AMH treatment. Thus, these findings highlight the potential of AMH in recovery from muscle atrophy.

Acute heat stress amplifies exercise-induced metabolomic perturbations and reveals variation in circulating amino acids in endurance-trained males

NEW FINDINGS

What is the central question of this study? Whole-body substrate utilisation is altered during exercise in hot environments, characterised by increased glycolytic metabolism: does heat stress alter the serum metabolome in response to high intensity exercise? What are the main finding and its importance? Alongside increases in glycolytic metabolite abundance, circulating amino acid concentrations are reduced following exercise under heat stress. Prior research has overlooked the impact of heat stress on protein metabolism during exercise, raising important practical implications for protein intake recommendations in the heat.

ABSTRACT

Using untargeted metabolomics, we aimed to characterise the systemic impact of environmental heat stress during exercise. Twenty-three trained male triathletes (V ̇ O 2 peak ${\dot V_{{{\rm{O}}_2}{\rm{peak}}}}$  = 64.8 ± 9.2 ml kg min-1 ) completed a 30-min exercise test in hot (35°C) and temperate (21°C) conditions. Venous blood samples were collected immediately pre- and post-exercise, and the serum fraction was assessed via untargeted 1 H-NMR metabolomics. Data were analysed via uni- and multivariate analyses to identify differences between conditions. Mean power output was higher in temperate (231 ± 36 W) versus hot (223 ± 31 W) conditions (P < 0.001). Mean heart rate (temperate, 162 ± 10 beats min-1 , hot, 167 ± 9 beats min-1 , P < 0.001), peak core temperature (Trec ), core temperature change (ΔTrec ) (P < 0.001) and peak rating of perceived exertion (P = 0.005) were higher in hot versus temperate conditions. Change in metabolite abundance following exercise revealed distinct clustering following multivariate analysis. Six metabolites increased (2-hydroxyvaleric acid, acetate, alanine, glucarate, glucose, lactate) in hot relative to temperate (P < 0.05) conditions. Leucine and lysine decreased in both conditions but to a greater extent in temperate conditions (P < 0.05). Citrate (P = 0.04) was greater in temperate conditions whilst creatinine decreased in hot conditions only (P > 0.05). Environmental heat stress increased glycolytic metabolite abundance and led to distinct alterations in the circulating amino acid availability, including increased alanine, glutamine, leucine and isoleucine. The data highlight the need for additional exercise nutrition and metabolism research, specifically focusing on protein requirements for exercise under heat stress.

Soymilk ingestion immediately after therapeutic exercise enhances rehabilitation outcomes in chronic stroke patients: A randomized controlled trial

PURPOSE

This study investigates the effects of an 8-weeks rehabilitation exercise plus soymilk ingestion immediately after exercise on functional outcomes in chronic stroke patients.

METHODS

Twenty-two stroke patients (age: 57-84 yrs; time since stroke onset: 2-19 yrs) participated and completed the study. A randomized, placebo-controlled and double-blind design was used. Participants were randomly allocated to either soymilk (SMS; n = 11) or placebo (PLA; n = 11) group and received identical 8-weeks rehabilitation intervention (3 sessions/week; 120 min/session) with corresponding treatment beverages. The physical and functional outcomes were evaluated before, during, and after the intervention.

RESULTS

The 8-weeks rehabilitation program enhanced functional outcomes of participants. The immediate soymilk ingestion after exercise additionally improved hand grip strength (p = 0.021), 8-feet walking speed (p = 0.019), walking performance per unit lean mass (p = 0.024), and 6-minute walk performance (6MWT, p = 0.016) compared with PLA after the intervention. However, the improvements in the total score for short physical performance battery (SPPB) and lean mass did not differ between groups.

CONCLUSION

Compared with rehabilitation alone, the 8-week rehabilitation program combined with immediate soymilk ingestion further improved walking speed, exercise endurance, grip strength, and muscle functionality in chronic stroke patients.

Early effects of eccentric contractions on muscle glucose uptake

Muscle-damaging eccentric exercise impairs muscle glucose uptake several hours to days after exercise. Little, however, is known about the acute effects of eccentric exercise on contraction- and insulin-induced glucose uptake. This study compares glucose uptake rates in the first hours following eccentric, concentric, and isometric contractions with and without insulin present. Isolated rat extensor digitorum longus muscles were exposed to either an eccentric, concentric, or isometric contraction protocol, and muscle contractions were induced by electric stimulation that was identical between contraction protocols. In eccentric and concentric modes, length changes of 0.6 or 1.2 mm were used during contractions. Both contraction- and insulin-induced glucose uptake were assessed immediately and 2 h after contractions. Glucose uptake increased significantly following all modes of contraction and was higher after eccentric contractions with a stretch of 1.2 mm compared with the remaining contraction groups when assessed immediately after contractions [eccentric (1.2 mm) > eccentric (0.6 mm), concentric (1.2 mm), concentric (0.6 mm), isometric > rest; P < 0.05]. After 2 h, contraction-induced glucose uptake was still higher than noncontracting levels, but with no difference between contraction modes. The presence of insulin increased glucose uptake markedly, but this response was blunted by, respectively, 39–51% and 29–36% ( P < 0.05) immediately and 2 h after eccentric contractions stretched 1.2 mm compared with concentric and isometric contractions. The contrasting early effects of eccentric contractions on contraction- and insulin-induced glucose uptake suggest that glucose uptake is impaired acutely following eccentric exercise because of reduced insulin responsiveness.

NEW & NOTEWORTHY This study shows that, in isolated rat muscle, muscle-damaging eccentric contractions result in a transient increase in contraction-induced glucose uptake compared with isometric and concentric contractions induced by identical muscle activation protocols. Furthermore, our results demonstrate that, in contrast, the insulin-stimulated glucose uptake is impaired immediately following muscle-damaging eccentric contractions.

Sago supplementation for recovery from cycling in a warm-humid environment and its influence on subsequent cycling physiology and performance

This study determined whether sago porridge ingested immediately after exercise (Exercise 1) in warm-humid conditions (30 ± 1°C, 71 ± 4 % RH; 20 km·h⁻¹ frontal airflow) conferred more rapid recovery, as measured by repeat performance (Exercise 2), compared to a control condition. Eight well-trained, male cyclists/triathletes (34 ± 9 y, VO₂peak 70 ± 10 ml·kg⁻¹·min⁻¹, peak aerobic power 413 ± 75 W) completed two 15-min time-trials pre-loaded with 15-min warm-up cycling following >24h standardization of training and diet. Mean power output was not different between trials during Exercise 1 (286 ± 67 vs. 281 ± 59 W), however, was reduced during Exercise 2 for control (274 ± 61 W) but not sago (283 ± 60 W) that led to a significant performance decrement (vs. Exercise 1) of 3.9% for control and an improvement (vs. control) of 3.7% for sago during Exercise 2 (P < 0.05). Sago ingestion was also associated with higher blood glucose concentrations during recovery compared to control. These results indicate that feeding sago during recovery from exercise in a warm-humid environment improves recovery of performance during a subsequent exercise bout when compared to a water-only control. As these effects were larger than the test-retest coefficient of variation for work completed during the 15-min time-trial (2.3%) it can be confidently concluded that the observed effects are real.

Exercise-induced rhabdomyolysis mechanisms and prevention: A literature review

Exercise-induced rhabdomyolysis (exRML), a pathophysiological condition of skeletal muscle cell damage that may cause acute renal failure and in some cases death. Increased Ca²⁺ level in cells along with functional degradation of cell signaling system and cell matrix have been suggested as the major pathological mechanisms associated with exRML. The onset of exRML may be exhibited in athletes as well as in general population. Previous studies have reported that possible causes of exRML were associated with excessive eccentric contractions in high temperature, abnormal electrolytes balance, and nutritional deficiencies possible genetic defects. However, the underlying mechanisms of exRML have not been clearly established among health professionals or sports medicine personnel. Therefore, we reviewed the possible mechanisms and correlated prevention of exRML, while providing useful and practical information for the athlete and general exercising population.

Effects of postexercise feeding of a supplemental carbohydrate and protein bar with or without astaxanthin from Haematococcus pluvialis to exercise-conditioned dogs

OBJECTIVE

To characterize the postprandial nutrient profiles of exercise-conditioned dogs fed a supplemental carbohydrate and protein bar with or without astaxanthin from Haematococcus pluvialis immediately after exercise.

ANIMALS

34 exercise-conditioned adult Husky-Pointer dogs.

PROCEDURES

The study had 2 phases. During phase 1, postprandial plasma glucose concentration was determined for dogs fed a bar containing 25% protein and 18.5% or 37.4% maltodextrin plus dextrin (rapidly digestible carbohydrate; RDC), or dry kibble (30% protein and 0% RDC) immediately after exercise. During phase 2, dogs were exercised for 3 days and fed a bar (25% protein and 37.4% RDC) with (CPA; n = 8) or without (CP; 8) astaxanthin or no bar (control; 8) immediately after exercise. Pre- and postexercise concentrations of plasma biochemical analytes and serum amino acids were determined on days 1 and 3.

RESULTS

Phase 1 postexercise glucose concentration was increased when dogs were provided the 37.4% RDC bar, but not 0% or 18.5% RDC. On day 3 of phase 2, the CPA group had the highest pre-exercise triglyceride concentration and significantly less decline in postexercise glucose concentration than did the CP and control groups. Mean glucose concentration for the CP and CPA groups was significantly higher than that for the control group between 15 and 60 minutes after bar consumption. Compared to immediately after exercise, branched-chain amino acid, tryptophan, leucine, and threonine concentrations 15 minutes after exercise were significantly higher for the CP and CPA groups, but were lower for the control group.

CONCLUSIONS AND CLINICAL RELEVANCE

Dogs fed a bar with 37.4% RDCs and 25% protein immediately after exercise had increased blood nutrient concentrations for glycogen and protein synthesis, compared with control dogs.

Nutrition habits in 24-hour mountain bike racers

We investigated seventy-four ultra-mountain bikers (MTBers) competing in the solo category in the first descriptive field study to detail nutrition habits and the most common food before during and after the 24 hour race using questionnaires. During the race, bananas (86.5%), energy bars (50.0%), apples (43.2%) and cheese (43.2%) were the most commonly consumed food, followed by bread (44.6%), rice (33.8%) and bananas (33.8%) after the race. Average fluid intake was 0.5 ± 0.2 l/h. The main beverage was isotonic sports drink (82.4%) during and pure water (66.2%) after the race. The most preferred four supplements in the four weeks before, the day before, during and after the race were vitamin C (35.1%), magnesium (44.6%), magnesium (43.2%) and branched-chain amino acids (24.3%), respectively. Total frequency of food intake (30.6 ± 10.5 times/24 hrs) was associated with fluid intake (r = 0.43, P = 0.04) and both were highest at the beginning of the race and lower during the night hours and the last race segment in a subgroup of twenty-three ultra-MTBers. Supplement intake frequency (6.8 ± 8.4 times/24 hrs) was highest during the night hours and lower at the beginning and end of the race. Elevated food and fluid intake among participants tracked across all race segments (P < 0.001). In conclusion, the nutrition strategy employed by ultra-MTBers was similar to those demonstrated in previous studies of ultra-cyclists with some exceptions among selected individuals.

Carbohydrate vs protein supplementation for recovery of neuromuscular function following prolonged load carriage

BACKGROUND

This study examined the effect of carbohydrate and whey protein supplements on recovery of neuromuscular function after prolonged load carriage.

METHODS

TEN MALE PARTICIPANTS (BODY MASS: 81.5 +/- 10.5 kg, age: 28 +/- 9 years, O(2)max: 55.0 +/- 5.5 ml.kg(-1).min(-1)) completed three treadmill walking tests (2 hr, 6.5 km.h(-1)), carrying a 25 kg backpack consuming 500 ml of either: (1) Placebo (flavoured water) [PLA], (2) 6.4% Carbohydrate Solution [CHO] or (3) 7.0% Whey Protein Solution [PRO]. For three days after load carriage, participants consumed two 500 ml supplement boluses. Muscle performance was measured before and at 0, 24, 48 and 72 h after load carriage, during voluntary and electrically stimulated contractions.

RESULTS

Isometric knee extension force decreased immediately after load carriage with no difference between conditions. During recovery, isometric force returned to pre-exercise values at 48 h for CHO and PRO but at 72 h for PLA. Voluntary activation decreased immediately after load carriage and returned to pre-exercise values at 24 h in all conditions (P = 0.086). During recovery, there were no differences between conditions for the change in isokinetic peak torque. Following reductions immediately after load carriage, knee extensor and flexor peak torque (60 degrees .s(-1)) recovered to pre-exercise values at 72 h. Trunk extensor and flexor peak torque (15 degrees .s(-1)) recovered to pre-exercise values at 24 h (P = 0.091) and 48 h (P = 0.177), respectively.

CONCLUSION

Recovery of neuromuscular function after prolonged load carriage is improved with either carbohydrate or whey protein supplementation for isometric contractions but not for isokinetic contractions.