Milk: An Effective Recovery Drink for Female Athletes

Challenges in Conducting Exercise Recovery Studies in Older Adults and Considerations for Future Research: Findings from a Nutritional Intervention Study

Maximising the potential benefit of resistance exercise (RE) programs by ensuring optimal recovery is an important aim of exercise prescription. Despite this, research surrounding recovery from RE in older adults is limited and inconsistent. The following randomised controlled trial was designed to investigate the efficacy of milk consumption for improving recovery from RE in older adults. However, the study encountered various challenges that may be applicable to similar studies. These include recruitment issues, a lack of measurable perturbations in muscle function following RE, and potential learning effects amongst participants. Various considerations for exercise research have arisen from the data which could inform the design of future studies in this area. These include (i) recruitment-consider ways in which the study design could be altered to aid recruitment or allow a longer recruitment period; (ii) learning effects and familiarisation-consider potential learning effects of outcome measures and adjust familiarisation accordingly; (iii) identify, validate and optimise protocols for outcome measures that are applicable for the specific population; (iv) adjust the exercise protocol according to the specific aims of the study (e.g., are you replicating a usual exercise bout or is the intent to cause large amounts of muscle damage?).

Acute effects of exercise-induced muscle damage on sprint and change of direction performance: A systematic review and meta-analysis

The aim of this study is to determine the acute effects of resistance and plyometric training on sprint and change of direction (COD) performance in healthy adults and adolescents. A systematic literature search was conducted via Medline, Cinahl, Scopus and SportDiscus databases for studies that investigated: 1) healthy male, female adults, or adolescents; and 2) measured sprint or change of direction performance following resistance and plyometric exercises. Studies were excluded if: 1) resistance or plyometric exercises was not used to induce muscle damage; 2) conducted in animals, infants, elderly; 3) sprint performance and/or agility performance was not measured 24 h post muscle damaging protocol. Study appraisal was completed using the Kmet Quality Scoring for Quantitative Study tool. Forest plots were generated to quantitatively analyse data and report study statistics for statistical significance and heterogeneity. The included studies (n = 20) revealed sprint and COD performance was significantly impaired up to 72 hr following resistance and plyometric exercises; both protocols significantly increased creatine kinase (CK), delayed-onset muscle soreness (DOMS) and decreased countermovement jump (CMJ) up to 72 hr. The systematic review of 20 studies indicated that resistance and plyometric training significantly impaired sprint and COD performance up to 72 hours post-exercise. Both training protocols elevated exercise-induced muscle damage (EIMD) markers (CK, DOMS) and decreased CMJ performance within the same timeframe.

Estimated Energy Expenditures and Energy Intakes of International Female Rugby Sevens Players in Five Days of a Training Camp and Competition Preparation

To understand the energy balance of international female rugby sevens (R7s) players in applied environments, this study estimated the energy intakes (EI) and total daily estimated energy expenditures (TDEE) during a five-day training camp (TRAIN) and phase of competition preparation (COMP) of equal duration. Tri-axial accelerometer devices were worn throughout both scenarios to estimate TDEE, whereas EI was estimated via self-reported food diaries. Energy deficits of -47% (TDEE_TRAIN: 14.6 ± 1.6 MJ·day^-1, EI_TRAIN: 7.7 ± 0.9 MJ·day^-1, p ≤ 0.001, d = 5.1) and -50% (TDEE_COMP: 15.5 ± 1.6 MJ·day^-1, EI_COMP: 7.7 ± 1.0 MJ·day^-1, p ≤ 0.001, d = 5.7) were observed throughout TRAIN (n = 11; age: 25 ± 4 years, height: 170 ± 6 cm, weight: 71 ± 7 kg) and COMP (n = 8; age: 25 ± 3 years, height: 172 ± 5 cm, weight: 72 ± 6 kg), respectively. Carbohydrate intakes were below the lower range of sports nutrition recommendations in both TRAIN (-62%; 2.3 ± 0.3 g·kg^-1 BM, p ≤ 0.001) and COMP (-60%; 2.4 ± 0.5 g·kg^-1 BM, p ≤ 0.001). For protein (TRAIN: 1.7 ± 0.4 g·kg^-1 BM, COMP: 1.5 ± 0.1 g·kg^-1 BM), intakes met the lower range of recommendations. Fat intake exceeded recommendations of the percentage of total EI (COMP: 39 ± 5%). Accordingly, the dietary strategies of international female R7s players may warrant optimization, as carbohydrate and fat intakes were less than optimal when compared to current performance-based sports nutrition guidelines.

The Acute Effects of Milk Consumption on Systemic Inflammation after Combined Resistance and Plyometric Exercise in Young Adult Females

High-intensity/impact exercise elicits a transient increase in inflammatory biomarkers. Consuming nutrient-dense wholefoods, like milk, following exercise may modulate post-exercise inflammation and aid recovery. We examined the effect of post-exercise skim milk consumption (versus an isoenergetic, isovolumetric carbohydrate [CHO] drink) on acute exercise-induced inflammation in untrained females. Using a randomized crossover design, 13 healthy females (age = 20 ± 2.3 y; BMI = 21.0 ± 1.1 kg/m²) completed two bouts of combined resistance/plyometric exercise followed by either skim milk (MILK) or CHO at 5-min and 1 h post-exercise. Serum interleukin [IL]-1β, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α) concentrations were measured at pre-exercise, 15-min, 75-min, 24 h, and 48 h post-exercise. IL-6 increased 15-min post-exercise vs. all other timepoints (time effect, p = 0.017). Between 24 and 48 h, IL-10 decreased and increased in the MILK and CHO conditions, respectively (interaction, p = 0.018). There were no significant effects for IL-1β or TNF-α. Relative concentrations of IL-1β (p = 0.049) and IL-10 (p = 0.028) at 48 h post-exercise were lower in MILK vs. CHO. Milk post-exercise did not influence the absolute concentration of pro-inflammatory cytokines; however, there were divergent responses for the anti-inflammatory cytokine, IL-10, and milk reduced the relative inflammatory response at 48 h (vs. CHO) for IL-1β and IL-10. This demonstrates the potential for milk to modulate inflammation post-exercise in this sample.

The Acute Effects of a Relative Dose of Pre-Sleep Protein on Recovery Following Evening Resistance Exercise in Active Young Men

The purpose of the present study was to assess the acute effects of pre-sleep consumption of isocaloric casein protein (CP), CP and whey protein (BLEND), or non-caloric control (CTRL) at a dose relative to lean body mass (LBM) on recovery following an evening lower-body resistance exercise (RE) bout. Fifteen active and previously resistance-trained males (age: 21 ± 1 years, body fat: 14.2 ± 2.7%) participated in this randomized, single-blind, crossover study. Participants performed an evening lower-body RE bout and were provided with 0.4 g/kg/LBM of whey protein (WP) supplement post-RE. A single dose of 0.6 g/kg/LBM of CP, 0.4 g/kg/LBM of CP and 0.2 g/kg/LBM WP (BLEND), or CTRL was consumed 30 min prior to sleep. Measurements of perceived recovery (visual analogue scales (VAS) for recovery, soreness, and fatigue), appetite (VAS for hunger, satiety, and desire to eat), as well as pressure-pain threshold (dolorimeter), average power, and peak torque (isokinetic dynamometry) of the right thigh muscles were assessed the following morning. Main effects of time were seen for all recovery variables (perceived recovery: F_2,28 = 96.753, p < 0.001, h_p² = 0.874; perceived fatigue: F_2,28 = 76.775, p < 0.001; h_p² = 0.846; perceived soreness: F_2,28 = 111.967, p < 0.001; h_p² = 0.889). A main effect of supplement was only seen for perceived recovery (F_2,28 = 4.869; p = 0.015; h_p² = 0.258), with recovery being 6.10 ± 2.58 mm greater in CP vs. BLEND (p = 0.033) and 7.51 ± 2.28 mm greater in CP than CTRL (p = 0.005). No main effects of supplement were seen in measures of perceived soreness, or fatigue (F_2,28 ≤ 2.291; p > 0.120; h_p² ≤ 0.141). No differences between supplements were found in perceived next-morning hunger (p = 0.06), satiety (p ≥ 0.227), or desire to eat (p = 0.528). Main effects of supplement were seen between BLEND and CP vs. CTRL for measures of pain-pressure threshold at the rectus femoris (F_2,28 = 9.377; p = 0.001; h_p² = 0.401), the vastus lateralis (F_2,28 = 10.887; p < 0.001; h_p² = 0.437), and the vastus medialis (F_2,28 = 12.113, p < 0.001; h_p² = 0.464). Values of peak torque and average power were similar between all supplement groups at 60°/sec (F_1.309,18.327 ≤ 1.994; p ≥ 0.173; h_p² ≤ 0.125), 180°/s (F_2,28 ≤ 1.221; p ≥ 0.310; h_p² ≤ 0.080), and 300°/sec (F_2,28 ≤ 2.854; p ≥ 0.074; h_p² ≤ 0.169). Pre-sleep consumption of CP and BLEND at a dose relative to LBM may enhance perceived overnight recovery to a greater extent than CTRL as a result of less muscle soreness the following morning after an acute evening RE bout.

Can Milk Affect Recovery from Simulated Team-Sport Match Play?

This study investigated the effects of cow's milk on recovery from repeated simulated team games (STGs) in females. Twenty female team-sport athletes completed an STG circuit (2x ~ 30 min, with 10 min 'half-time'). Measures of muscle function, soreness and tiredness, symptoms of stress and serum markers of muscle damage and oxidative stress were determined pre- and 24 h, 48 h, 72 h and 96 h following the circuit. At 48 h, a second STG was completed. Sprint performance (5 m, 15 m), lap time, countermovement jump (CMJ), heart rate and RPE were recorded during each STG. Immediately following each STG, participants consumed either 500 mL of cow's milk (MILK) or 500 mL of an energy-matched carbohydrate (CHO) solution. Compared to CHO, MILK had a beneficial effect in attenuating losses in peak torque for knee extension (60°/s) (likely; effect size (ES) = 0.26 to 0.28) knee flexion (60°/s) (likely; ES = 0.45 to 0.61). A benefit for MILK was observed for 5 m sprint (possible-likely; ES = 0.40 to 0.58), 10 m sprint (likely; ES = 0.30 to 0.53) and symptoms of stress (likely-very likely, small). Mostly unclear outcomes for other variables were observed. For STG variables, trivial (HR, CMJ) and unclear (5 m sprint, 15 m sprint, lap-time, RPE) outcomes were recorded. In conclusion, the consumption of 500 mL of milk attenuated losses in muscle function and perceptions of stress following repeated simulated team-sports games. However, further investigation is warranted to determine whether MILK can influence subsequent team-sport performance.

Milk and resistance exercise intervention to improve muscle function in community-dwelling older adults at risk of sarcopenia (MIlkMAN): protocol for a pilot study

INTRODUCTION

Sarcopenia is a progressive muscle disorder characterised by decline in skeletal muscle mass, strength and function leading to adverse health outcomes, including falls, frailty, poor quality of life and death. It occurs more commonly in older people and can be accelerated by poor diet and low physical activity. Intervention studies incorporating higher dietary protein intakes or protein supplementation combined with resistance exercise (RE) have been shown to limit muscle function decline. However, less is known about the role of whole foods in reducing the risk of sarcopenia. Milk is a source of high-quality nutrients, which may be beneficial for skeletal muscle. This pilot study examines the feasibility and acceptability of milk consumption with RE to improve muscle function in community-dwelling older adults at risk of sarcopenia.

METHODS AND ANALYSIS

30 older adults aged ≥65 years will be randomly allocated to three groups: 'whole milk+RE', 'skimmed milk+RE' or 'control drink+RE'. Assessments will take place in participants' homes, including screening (milk allergies, grip strength, walking speed), baseline and postintervention health and function. All participants will undertake a structured RE intervention twice a week for 6 weeks at a local gym, followed by the consumption of 500 mL of whole or skimmed milk (each ~20 g of protein) or an isocaloric control drink and another 500 mL at home. Participants' views about the study will be assessed using standardised open-ended questions. The primary outcomes include feasibility and acceptability of the intervention with recruitment, retention and intervention response rates. Analyses will include descriptive statistics, exploration of qualitative themes and intervention fidelity.

ETHICS AND DISSEMINATION

Outputs include pilot data to support funding applications; public involvement events; presentation at conferences and peer-reviewed publication.

TRIAL REGISTRATION NUMBER

ISRCTN13398279; Pre-results.

Consumption of an Anthocyanin-Rich Extract Made From New Zealand Blackcurrants Prior to Exercise May Assist Recovery From Oxidative Stress and Maintains Circulating Neutrophil Function: A Pilot Study

Aim: To evaluate blackcurrant anthocyanin-rich extract (BAE) consumption on time- and dose-dependent plasma anthocyanin bioavailability and conduct a pilot study to explore the potential effect of BAE in promoting recovery from exercise-induced oxidative stress, and maintenance of circulating neutrophil function.

Methods: Time- and dose-dependent blackcurrant anthocyanin bioavailability was assessed using LC-MS in 12 participants over 6 h after the ingestion of a placebo or BAE containing 0.8, 1.6, or 3.2 mg/kg total anthocyanins. In a separate pilot intervention exercise trial, 32 participants consumed either a placebo or 0.8, 1.6, or 3.2 mg/kg BAE (8 individuals per group), and then 1 h later performed a 30 min row at 70% VO₂max. Blood was collected during the trial for oxidative, antioxidant, inflammatory, and circulating neutrophil status.

Results: Consumption of BAE caused a time- and dose-dependent increase in plasma anthocyanins, peaking at 2 h after ingestion of 3.2 mg/kg BAE (217 ± 69 nM). BAE consumed 1 h prior to a 30 min row had no effect on plasma antioxidant status but hastened the recovery from exercise-induced oxidative stress: By 2 h recovery, consumption of 1.6 mg/kg BAE prior to exercise caused a significant (P < 0.05) 34 and 32% decrease in post-exercise plasma oxidative capacity and protein carbonyl levels, respectively, compared to placebo. BAE consumption prior to exercise dose-dependently attenuated a small, yet significant (P < 0.01) transient 13 ± 2% decline in circulating neutrophils observed in the placebo group immediately post-exercise. Furthermore, the timed consumption of either 1.6 or 3.2 mg/kg BAE attenuated a 17 ± 2.4% (P < 0.05) decline in neutrophil phagocytic capability of opsonised FITC-Escherichia coli observed 6 h post-exercise in the placebo group. Similarly, a dose-dependent increase in neutrophil surface expression of complement receptor-3 complex (CR3, critical for effective phagocytosis of opsonised microbes), was observed 6 h post-exercise in both 1.6 and 3.2 mg/kg BAE intervention groups.

Conclusions: Consumption of BAE (>1.6 mg/kg) 1 h prior to exercise facilitated recovery from exercise-induced oxidative stress and preserved circulating neutrophil function. This study provides data to underpin a larger study designed to evaluate the efficacy of timed BAE consumption on post-exercise recovery and innate immunity.

Impact of cow's milk intake on exercise performance and recovery of muscle function: a systematic review

Dairy products are thought to improve recovery after both resistance and endurance exercises due to their nutritional proprieties. We systematically reviewed the effects of dairy product intake on exercise performance and recovery of muscle function in humans. A literature search was conducted in the MEDLINE (via PubMed) and Web of Science databases from their inception to 15th April 2018. The initial search retrieved 7708 articles, and a total of 11 studies were finally included after applying inclusion and exclusion criteria. All the selected studies were conducted with cow's milk. Whereas some studies found significant positive effect of cow's milk on exercise performance and recovery of muscle function, others did not find any effect. These controversies could be due to the heterogeneity of cow's milk ingestion (e.g., amount of cow's milk, timing of consuming the cow's milk), to the type of intervention, and to the large heterogeneity of outcomes measured. Limited studies exist examining the effects of cow's milk consumption and its influence on exercise performance and recovery of muscle function, therefore further studies are needed to draw more definitive conclusions.

Pre-Sleep Consumption of Casein and Whey Protein: Effects on Morning Metabolism and Resistance Exercise Performance in Active Women

Consuming milk proteins (casein (CP) and whey (WP)) at night before sleep has been shown to positively influence next morning resting metabolic rate (RMR). No data exist regarding the effect of pre-sleep consumption of CP and WP on the ability to perform resistance exercise (RE) the following morning. The present study compared the effects of low (24 g) and high (48 g) doses of CP and WP and a non-energetic placebo (PLA) consumed 30 min before sleep on morning RMR, and RE performance. Nine active women participated in this randomized, double-blind, crossover study. Next morning RMR was measured via indirect calorimetry. RE was performed on six machines for 2 sets of 10 repetitions, and a 3rd set to failure at 60% of one-repetition maximum to calculate RE volume (weight lifted × sets × repetitions). Magnitude based inferences were used. Compared to the PLA, 48 g CP had a likely increase in RMR (4.0 ± 4.8%) and possibly trivial (1.1 ± 7.0%) effect on RE volume. There were no clear effects of 24 g CP, 24 g and 48 g of WP on RMR and RE volume. In conclusion, 48 g CP elicited favorable changes in morning RMR, with only trivial changes in RE performance.

Investigating the Nutritional and Recovery Habits of Tennis Players

In this study, the nutritional and recovery habits of tennis players pre-, during, and post-match-play were investigated. Seventy tennis players completed a bespoke nutrition and recovery habits questionnaire, with questions related to the following areas: match preparation, intra-match nutritional habits, situation dependent variables, and post-match nutrition and recovery. On match day-1, the consumption of balanced meals consisting of carbohydrate (CHO), fat and protein, with some micronutrient considerations were reported by 51% of players. On match-days, CHOs were prioritised prior to match-play with CHO dominant meals consumed by the majority of players. During matches, all players adopted a nutritional strategy, with water (94%), banana(s) (86%) and sports drinks (50%) commonly used. Carbohydrate rich nutritional aids, including sports drinks (80%) and energy gels (26%) were utilised more readily during long matches (>2 h). The day after match-play, 39% of players reported the consumption of “nothing specific”. Multiple post-match recovery strategies were adopted by 80% of players, with foam rolling (77%), ice baths (40%), protein shake intake (37%) and hot baths (26%) most used. Findings indicate highly variable eating and recovery habits in tennis players pre-, during and post-match-play, with scope for improved practices.