Impact of increased protein intake in older adults: a 12-week double-blind randomised controlled trial.

BACKGROUND: Emerging evidence suggests health-promoting properties of increased protein intake. There is increased interest in plant protein but a dearth of information in relation to its impact on muscle function. The objective of the present work was to examine the impact of intake of different types of proteins on muscle functional parameters including handgrip strength, biomarkers of metabolic health, sleep quality and quality of life in a group of older adults. METHODS: Healthy men and women aged 50 years and older entered a double-blinded, randomised, controlled nutritional intervention study with three parallel arms: high plant protein, high dairy protein and low protein. Participants consumed once daily a ready-to-mix shake (containing 20 g of protein in high protein groups) for 12 weeks. Changes in handgrip and leg strength, body composition, metabolic health, quality of life and sleep quality were analysed by linear mixed models in an intention-to-treat approach. RESULTS: Eligible participants (n = 171) were randomly assigned to the groups (plant: n = 60, dairy: n = 56, low protein: n = 55) and 141 completed the study. Handgrip strength increased after the intervention (Ptime = 0.038), with no significant difference between the groups. There was no significant difference between groups for any other health outcomes. CONCLUSIONS: In a population of older adults, increasing protein intake by 20 g daily for 12 weeks (whether plant-based or dairy-based) did not result in significant differences in muscle function, body composition, metabolic health, sleep quality or quality of life, compared with the low protein group.

Mental calculation increases physiological postural tremor, but does not influence physiological goal-directed kinetic tremor.

PURPOSE: During a cognitive effort, an increase in cortical electrical activity, functional alterations in the anterior cingulate cortex, and modifications in cortical inputs to the active motor units have been reported. In light of this, an increase in tremor could be anticipated as result of a mental task. In the present work, we tested this hypothesis. METHODS: In 25 individuals, tremor was measured with a three-axial accelerometer during 300 s of postural and goal-directed tasks performed simultaneously to mental calculation, or during control (same tasks without mental calculation). Hand and finger dexterity were also evaluated. Electromyographic (EMG) recordings from the extensor digitorum communis were collected during the postural task. RESULTS: Hand and finger dexterity was negatively affected by the mental task (p = .003 and p = .00005 respectively). During mental calculation, muscle tremor increased in the hand postural (+ 29%, p = .00005) but not in the goal-directed task (- 1.5%, p > .05). The amplitude of the main frequency peak also increased exclusively in the hand postural task (p = .028), whilst no shift in the position of the main frequency peak was observed. EMG was not affected. CONCLUSION: These results support the position of the contribution of a central component in the origin of physiological hand postural tremor. It is suggested that the different effect of mental calculation on hand postural and goal-directed tasks can be attributed to the different origins and characteristics of hand postural and goal-directed physiological tremor.

Moringa oleifera Leaf Extract Protects C2C12 Myotubes against H2O2-Induced Oxidative Stress.

The imbalance between reactive oxygen species (ROS) production and antioxidant defense systems leads to macromolecule and tissue damage as a result of cellular oxidative stress. This phenomenon is considered a key factor in fatigue and muscle damage following chronic or high-intensity physical exercise. In the present study, the antioxidant effect of Moringa oleifera leaf extract (MOLE) was evaluated in C2C12 myotubes exposed to an elevated hydrogen peroxide (H2O2) insult. The capacity of the extract to influence the myotube redox status was evaluated through an analysis of the total antioxidant capacity (TAC), glutathione homeostasis (GSH and GSSG), total free thiols (TFT), and thioredoxin (Trx) activity, as well as the enzyme activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) and transferase (GST). Moreover, the ability of MOLE to mitigate the stress-induced peroxidation of lipids and oxidative damage (TBARS and protein carbonyls) was also evaluated. Our data demonstrate that MOLE pre-treatment mitigates the highly stressful effects of H2O2 in myotubes (1 mM) by restoring the redox status (TFT, Trx, and GSH/GSSG ratio) and increasing the antioxidant enzymatic system (CAT, SOD, GPx, GST), thereby significantly reducing the TBARs and PrCAR levels. Our study provides evidence that MOLE supplementation has antioxidant potential, allowing myotubes better able to cope with an oxidative insult and, therefore, could represent a useful nutritional strategy for the preservation of muscle well-being.

Low-volume HIIT and MICT speed V̇o2 kinetics during high-intensity "work-to-work" cycling with a similar time-course in type 2 diabetes.

We assessed the rates of adjustment in oxygen uptake (V̇o2) and muscle deoxygenation [i.e., deoxygenated hemoglobin and myoglobin, (HHb + Mb)] during the on-transition to high-intensity cycling initiated from an elevated baseline (work-to-work, w-to-w) before training and at weeks 3, 6, 9, and 12 of low-volume high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) in type 2 diabetes (T2D). Participants were randomly assigned to MICT (n = 11, 50 min of moderate-intensity cycling), HIIT (n = 8, 10 × 1 min of high-intensity cycling separated by 1 min of light cycling) or nonexercising control (n = 9) groups. Exercising groups trained three times per week. Participants completed two w-to-w transitions at each time point consisting of sequential step increments to moderate- and high-intensity work-rates. [HHb + Mb] kinetics were measured by near-infrared spectroscopy at the vastus lateralis muscle. The pretraining time constant of the primary phase of V̇o2 (V̇o2 τp) and the amplitude of the V̇o2 slow component (V̇o2As) of the high-intensity w-to-w bout decreased (P < 0.05) by a similar magnitude at week 3 of training in both MICT (from 56 ± 9 to 43 ± 6 s, and from 0.17 ± 0.07 to 0.09 ± 0.05 L/min, respectively) and HIIT (from 56 ± 8 to 42 ± 6 s, and from 0.18 ± 0.05 to 0.09 ± 0.08 L/min, respectively) with no further changes thereafter. No changes were reported in controls. The parameter estimates of Δ[HHb + Mb] remained unchanged in all groups. MICT and HIIT elicited comparable improvements in V̇o2 kinetics without changes in muscle deoxygenation kinetics during high-intensity exercise initiated from an elevated baseline in T2D despite training volume and time commitment being ∼50% lower in the HIIT group.NEW & NOTEWORTHY Three weeks of high-intensity interval training and moderate-intensity continuous training decreased the time constant of the primary phase of oxygen uptake (V̇o2) and amplitude of the V̇o2 slow component during a high-intensity exercise initiated from an elevated baseline, a protocol that mimics the abrupt metabolic transitions akin to those in daily life, in type 2 diabetes. These V̇o2 kinetics improvements were maintained until the end of the 12-wk intervention without changes in muscle deoxygenation kinetics.

Resting Metabolic Rate in Female Rugby Players: Differences in Measured Versus Predicted Values.

ABSTRACT: O'Neill, JERG, Walsh, CS, McNulty, SJ, Gantly, HC, Corish, ME, Crognale, D, and Horner, K. Resting metabolic rate in female rugby players: differences in measured versus predicted values. J Strength Cond Res 36(3): 845-850, 2022-This study investigated (a) the accuracy of resting metabolic rate (RMR) prediction equations in female rugby players and (b) factors that might explain poor prediction accuracy in some individuals. Resting metabolic rate was assessed in 36 female elite and subelite rugby players (age: 18-35 years, fat-free mass (FFM): 43-63 kg, fat mass %: 15-41%). After pretest standardization (24-hour exercise avoidance and 12-hour overnight fast), RMR was measured by indirect calorimetry and compared with predicted values determined by Harris-Benedict, Cunningham, Ten Haaf, Jagim and Watson equations. Body composition was assessed by air displacement plethysmography, muscle damage indicated by creatine kinase, and risk of low energy availability (LEA) by LEA in Females Questionnaire. Measured RMR was 1,651 ± 167 kcal·d-1. The Cunningham, Ten Haaf, and Watson (body mass) predicted values did not differ from measured (p > 0.05), while all other predicted values differed significantly (p < 0.001). Individually, prediction accuracy to within 10% varied widely depending on the equation used (range 44% [n = 16] to 86% [n = 31]). Three of the 5 individuals whose values were outside 10% of the measured value using the best performing Ten Haaf FFM equation could be explained by muscle damage or LEA. These measures may be useful to assist in understanding why measured RMR may be lower or higher than predicted in some athletes. Overall, the Ten Haaf equations showed the best accuracy, suggesting these equations may be most suitable for this population. The findings demonstrate the importance of considering the population studied when determining the most appropriate prediction equation to use.

Moringa oleifera Leaf Extract Upregulates Nrf2/HO-1 Expression and Ameliorates Redox Status in C2C12 Skeletal Muscle Cells.

Moringa oleifera is a multi-purpose herbal plant with numerous health benefits. In skeletal muscle cells, Moringa oleifera leaf extract (MOLE) acts by increasing the oxidative metabolism through the SIRT1-PPARα pathway. SIRT1, besides being a critical energy sensor, is involved in the activation related to redox homeostasis of transcription factors such as the nuclear factor erythroid 2-related factor (Nrf2). The aim of the present study was to evaluate in vitro the capacity of MOLE to influence the redox status in C2C12 myotubes through the modulation of the total antioxidant capacity (TAC), glutathione levels, Nrf2 and its target gene heme oxygenase-1 (HO-1) expression, as well as enzyme activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and transferase (GST). Moreover, the impact of MOLE supplementation on lipid peroxidation and oxidative damage (i.e., TBARS and protein carbonyls) was evaluated. Our results highlight for the first time that MOLE increased not only Nrf2 and HO-1 protein levels in a dose-dependent manner, but also improved glutathione redox homeostasis and the enzyme activities of CAT, SOD, GPx and GST. Therefore, it is intriguing to speculate that MOLE supplementation could represent a valuable nutrition for the health of skeletal muscles.

The effects of a combined bodyweight-based and elastic bands resistance training, with or without protein supplementation, on muscle mass, signaling and heat shock response in healthy older people.

This investigation sought to determine the effects of twelve weeks of resistance exercise training in addition to protein supplementation on body composition, markers of muscle atrophy/hypertrophy and heat shock response (HSR) in healthy older adults. Thirty-eight healthy sedentary participants (M/F, 18/20; age, 63.5 ±â€¯4.4 y) were randomly assigned to four groups: I) PLACEBO: no training, receiving placebo sachets; II) NUTRITION: no training, receiving protein supplementation sachets; III) EXERCISE PLACEBO: training, placebo sachets and IV) EXERCISE NUTRITION: training, receiving protein sachets. The resistance training (using bodyweight and elastic bands) consisted of 45 min supervised training sessions, 3×/week. Participants from both exercise groups increased their total lean body mass (from 48.4 ±â€¯8.7 to 49.2 ±â€¯8.7 kg and from 44.9 ±â€¯7.8 to 45.9 ±â€¯8.1 kg, average of gain ~0.8 and 1 kg, placebo and nutrition respectively) and improved results in physical tests. Exercise nutrition group also reduced their body fat (from 34.8 ±â€¯7.3 to 32.9 ±â€¯7.4%), increased the expression of proteins/gene involved on the HSR, S6 and eEF2, while FOXO3 and Murf1 were reduced. Expression of MHC-I was reduced in both exercise groups while MHC-IIa increased, with no effect of protein supplementation alone. Body-weight and elastic bands based resistance exercise prompted, in healthy older people, improvements in body composition and muscle function. When protein supplementation was added to the people engaged in resistance training, improvements in fat mass and changes in skeletal muscle signaling were detected, favoring protein synthesis pathways and the protective heat shock response.

Elevated levels of extracellular heat-shock protein 72 (eHSP72) are positively correlated with insulin resistance in vivo and cause pancreatic ß-cell dysfunction and death in vitro.

eHSP72 (extracellular heat-shock protein 72) is increased in the plasma of both types of diabetes and is positively correlated with inflammatory markers. Since aging is associated with a low-grade inflammation and IR (insulin resistance), we aimed to: (i) analyse the concentration of eHSP72 in elderly people and determine correlation with insulin resistance, and (ii) determine the effects of eHSP72 on ß-cell function and viability in human and rodent pancreatic ß-cells. Fasting blood samples were collected from 50 older people [27 females and 23 males; 63.4±4.4 years of age; BMI (body mass index)=25.5±2.7 kg/m2]. Plasma samples were analysed for eHSP72, insulin, TNF (tumour necrosis factor)-α, leptin, adiponectin and cortisol, and glycaemic and lipid profile. In vitro studies were conducted using rodent islets and clonal rat and human pancreatic ß-cell lines (BRIN-BD11 and 1.1B4 respectively). Cells/islets were incubated for 24 h with eHSP72 (0, 0.2, 4, 8 and 40 ng/ml). Cell viability was measured using three different methods. The impact of HSP72 on ß-cell metabolic status was determined using Seahorse Bioscience XFe96 technology. To assess whether the effects of eHSP72 were mediated by Toll-like receptors (TLR2/TLR4), we co-incubated rodent islets with eHSP72 and the TLR2/TLR4 inhibitor OxPAPC (oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine; 30 µg/ml). We found a positive correlation between plasma eHSP72 and HOMA-IR (homoeostasis model assessment of IR) (r=0.528, P<0.001), TNF-α (r=0.389, P<0.014), cortisol (r=0.348, P<0.03) and leptin/adiponectin (r=0.334, P<0.03). In the in vitro studies, insulin secretion was decreased in an eHSP72 dose-dependent manner in BRIN-BD11 cells (from 257.7±33 to 84.1±10.2 µg/mg of protein per 24 h with 40 ng/ml eHSP72), and in islets in the presence of 40 ng/ml eHSP72 (from 0.48±0.07 to 0.33±0.009 µg/20 islets per 24 h). Similarly, eHSP72 reduced ß-cell viability (at least 30% for BRIN-BD11 and 10% for 1.1B4 cells). Bioenergetic studies revealed that eHSP72 altered pancreatic ß-cell metabolism. OxPAPC restored insulin secretion in islets incubated with 40 ng/ml eHSP72. In conclusion, we have demonstrated a positive correlation between eHSP72 and IR. In addition, we suggest that chronic eHSP72 exposure may mediate ß-cell failure.

Neuromuscular electrical stimulation can elicit aerobic exercise response without undue discomfort in healthy physically active adults.

Recent studies have suggested that subtetanic neuromuscular electrical stimulation (NMES) protocols applied to the quadriceps and hamstrings may have potential as an alternative aerobic exercise modality. However, its tolerability and effectiveness in the physically active population has been questioned. The primary purpose of this study was to measure physiological and subjective responses to a modified subtetanic NMES protocol in a physically active adult population. Furthermore, the effect of habituation to stimulation on tolerability, the repeatability of response on separate days, and the differences in male and female responses to stimulation were assessed. Oxygen uptake (V[Combining Dot Above]O(2)), heart rate (HR), blood lactate (BLa), rate of perceived exertion, and subjective discomfort were measured in 16 participants (8 men and 8 women) throughout a subtetanic NMES protocol performed at incremental intensities to subjective comfort threshold on 2 separate days, before and after 9 NMES habituation sessions. Peak physiological responses observed at subjective comfort threshold were consistent with therapeutic aerobic exercise intensities (51.5 ± 10.9% V[Combining Dot Above]O(2)max; 72.0 ± 10.9% HRmax; 4.7 ± 2.7 mMol BLa). Peak V[Combining Dot Above]O(2) and current intensity achieved were significantly higher (p < 0.05), yet perceived discomfort was unchanged, after the period of habituation. However, physiological and subjective responses at equivalent stimulation intensities remained unchanged on different days. Male participants showed higher values than female participants. These results suggest that subtetanic NMES can elicit a consistent aerobic exercise response without undue discomfort and could be considered as an alternative exercise modality.

Neuro-muscular electrical stimulation training enhances maximal aerobic capacity in healthy physically active adults.

Previous research has shown that a novel form of neuro-muscular electrical stimulation (NMES) can be used to bring about aerobic training effects in sedentary adults and in patients with heart failure. However, it is not clear whether this form of NMES could induce a significantly strong cardiovascular exercise effect in a more active group where a greater stimulus is required for training. In this study we investigated the aerobic training effects of repeated exposure to low frequency NMES in a group of physically active healthy adults. Results demonstrated a clinically and statistically significant training response following 18 trainings sessions, suggesting that this form of NMES has a role to play in cardiovascular exercise training in a physically active healthy population.