Stuart M Phillips

Aerobic and resistance exercise (RE) induce distinct molecular responses. One hypothesis is that these responses are antagonistic and unfavorable for the anabolic response to RE when concurrent exercise is performed. This thesis may also depend on the participants' training status and concurrent exercise order. We measured free‐living myofibrillar protein synthesis (MyoPS) rates and associated molecular responses to resistance‐only and concurrent exercise (with different exercise orders), before and after training. Moderately active men completed one of three exercise interventions (matched for age, baseline strength, body composition, and aerobic capacity): resistance‐only exercise (RE, n = 8), RE plus high‐intensity interval exercise (RE+HIIE, n = 8), or HIIE+RE (n = 9). Participants trained 3 days/week for 10 weeks; concurrent sessions were separated by 3 h. On the first day of Weeks 1 and 10 …

Ribosomes are essential cellular machinery for protein synthesis. It is hypothesised that ribosome content supports muscle growth and that individuals with more ribosomes have greater increases in muscle size following resistance training (RT). Aerobic conditioning (AC) also elicits distinct physiological adaptations; however, no measures of ribosome content following AC have been conducted. We used ribosome‐related gene expression as a proxy measure for ribosome content and hypothesised that AC and RT would increase ribosome‐related gene expression. Fourteen young men and women performed 6 weeks of single‐legged AC followed by 10 weeks of double‐legged RT. Muscle biopsies were taken following AC and following RT in the aerobically conditioned (AC+RT) and unconditioned (RT) legs. No differences in regulatory genes (Ubf, Cyclin D1, Tif‐1a and Polr‐1b) involved in ribosomal …

Background. The growth in participation in collegiate athletics has been accompanied by increased sport-related injuries. The complex and multifactorial nature of sports injuries highlights the importance of monitoring athletes prospectively using a novel and integrated biopsychosocial approach, as opposed to contemporary practices that silo these facets of health. Methods. Data collected over two competitive basketball seasons were used in a principal component analysis (PCA) model with the following objectives: (i) investigate whether biomechanical PCs (i.e., on-court and countermovement jump (CMJ) metrics) were correlated with psychological state across a season and (ii) explore whether subject-specific significant fluctuations could be detected using minimum detectable change statistics. Weekly CMJ (force plates) and on-court data (inertial measurement units), as well as psychological state (questionnaire) data, were collected on the female collegiate basketball team for two seasons. Results. While some relationships (n = 2) were identified between biomechanical PCs and psychological state metrics, the magnitude of these associations was weak (r = |0.18-0.19|, ), and no other overarching associations were identified at the group level. However, post-hoc case study analysis showed subject-specific relationships that highlight the potential utility of red-flagging meaningful fluctuations from normative biomechanical and psychological patterns. Conclusion. Overall, this work demonstrates the potential of advanced analytical modeling to characterize components of and detect statistically and clinically relevant fluctuations in student …

The International Olympic Committee (IOC) recently published a framework on fairness, inclusion, and nondiscrimination on the basis of gender identity and sex variations. Although we appreciate the IOC's recognition of the role of sports science and medicine in policy development, we disagree with the assertion that the IOC framework is consistent with existing scientific and medical evidence and question its recommendations for implementation. Testosterone exposure during male development results in physical differences between male and female bodies; this process underpins male athletic advantage in muscle mass, strength and power, and endurance and aerobic capacity. The IOC's “no presumption of advantage” principle disregards this reality. Studies show that transgender women (male‐born individuals who identify as women) with suppressed testosterone retain muscle mass, strength, and other …

The International Olympic Committee (IOC) recently published a Framework on Fairness, Inclusion, and Non-discrimination on the Basis of Gender Identity and Sex Variations. Although we appreciate the IOC's recognition of the role of sports science and medicine in policy development, we disagree with the assertion that the IOC Framework is consistent with existing scientific and medical evidence and question its recommendations for implementation. Testosterone exposure during male development results in physical differences between male and female bodies; this process underpins male athletic advantage in muscle mass, strength and power, and endurance and aerobic capacity. The IOC's ”no presumption of advantage” principle disregards this reality. Studies show that transgender women (male-born individuals who identify as women) with suppressed testosterone retain muscle mass, strength, and other physical advantages compared to females; male performance advantage cannot be eliminated with testosterone suppression. The IOC's concept of “meaningful competition” is flawed because fairness of category does not hinge on closely-matched performances. The female category ensures fair competition for female athletes by excluding male advantages. Case-by-case testing for transgender women may lead to stigmatisation and cannot be robustly managed in practice. We argue that eligibility criteria for female competition must consider male development rather than relying on current testosterone levels. Female athletes should be recognized as the key stakeholders in the consultation and decision-making processes. We urge …

Stuart M. Phillips, Ph. D., FACSM, is a professor and tier 1 Canada research chair at the Department of Kinesiology, McMaster University. His research focuses on skeletal muscle and its regulation through resistance exercise and nutrition.Jasmin K. Ma, Ph. D., ACSM/NCHPAD-CIFT, is an assistant professor teaching at the School of Kinesiology, University of British Columbia; a clinician investigator at Arthritis Research Canada; and an investigator at the International Collaboration on Repair Discoveries. Her research focuses on improving strength-training participation among people with chronic disease and disability and the codevelopment of tailored physical activity interventions.

Regular physical activity (PA) and exercise alleviate mental health and age-related physical declines in older adults; however, strategies are needed to help older adults engage in PA and exercise. Live online video may be a viable mode of delivery for exercise programs. Thirty-one sedentary community-dwelling older adults (65-80 years) were randomized to an 8-week live online exercise program (ACTIVE, n= 16; age 70±4 years; 69% women) or waitlist control (CON, n= 15; age 72±5 years; 87% women) group. Quantitative effectiveness data were collected pre-and post-intervention and included accelerometry-derived PA levels and mental health (depression, anxiety, and loneliness). Feasibility outcomes included attendance and participant satisfaction. Semi-structured interviews were optional for all participants after completing the online exercise program (n= 22; ACTIVE= 12; CON= 10; 73% women). The …

This study investigated sex differences in, and the effect of protein supplementation on, bone metabolism during a 36-h military field exercise. Forty-four British Army Officer cadets (14 women) completed a 36-h field exercise. Participants consumed either their habitual diet [n= 14 women (Women) and n= 15 men (Men Controls)] or the habitual diet with an additional 46.6 g· day− 1 of protein for men [n= 15 men (Men Protein)]. Women and Men Protein were compared with Men Controls to examine the effect of sex and protein supplementation. Circulating markers of bone metabolism were measured before, 24 h after (postexercise), and 96 h after (recovery) the field exercise. Beta C-telopeptide cross links of type 1 collagen and cortisol were not different between time points or Women and Men Controls (P≥ 0.094). Procollagen type I N-terminal propeptide decreased from baseline to postexercise (P< 0.001) and …

We aimed to determine whether there was a relationship between pre-immobilization skeletal muscle size and the magnitude of muscle atrophy following 14 days of unilateral lower limb immobilization. Our findings (n = 30) show that pre-immobilization leg fat-free mass and quadriceps cross-sectional area (CSA) were unrelated to the magnitude of muscle atrophy. However, sex-based differences may be present, but confirmatory work is required. In women, pre-immobilization leg fat-free mass and CSA were associated with changes in quadriceps CSA after immobilization (n = 9, r2 = 0.54–0.68; P < 0.05). The extent of muscle atrophy is not affected by initial muscle mass, but there is potential for sex-based differences.

We examined muscle proteostasis in obese insulin-resistant (OIR) individuals to determine whether endurance exercise could positively influence proteome dynamics in this population. Male OIR (n = 3) and lean, healthy controls (LHC; n = 4) were recruited and underwent a 14-d measurement protocol of daily deuterium oxide (D2O) consumption and serial biopsies of vastus lateralis muscle. The OIR group then completed 10-weeks of high-intensity interval training (HIIT), encompassing 3 sessions per week of cycle ergometer exercise with 1 min intervals at 100 % maximum aerobic power (Wmax) interspersed by 1 min recovery periods. The number of intervals per session progressed from 4 to 8, and during weeks 8-10 the 14-d measurement protocol was repeated. The abundance and turnover rates of 880 and 301 proteins, respectively, were measured. OIR and LHC muscle exhibited 352 differences (p < 0.05, false discovery rate (p < 0.05) differences in protein turnover. OIR muscle was enriched with markers of metabolic stress, protein misfolding and components of the ubiquitin-proteasome system, and the turnover rate of many of these proteins was less compared to LHC muscle. HIIT altered the abundance of 53 proteins and increased the turnover rate of 22 proteins (p < 0.05) in OIR muscle and tended to restore proteostasis, evidenced by increasing muscle protein turnover rates and normalizing proteasome composition in OIR participants. In conclusion, obesity and insulin resistance are associated with compromised muscle proteostasis, which can be partially restored by endurance exercise.

A method of improving at least one of the following in an individual: lean mass, muscle strength, cognition, systemic inflammation levels, blood cholesterol levels, blood triglyc eride levels and glucose tolerance is provided, comprising administering to the individual a multi-nutrient composition a protein, creatine, vitamin D, calcium and an n-3 fatty acid. 14 Claims, 9 Drawing Sheets

Supplementation with Fortetropin® (FOR), a naturally occurring component from fertilized egg yolks, reduces circulating myostatin concentration. We hypothesized that FOR would mitigate muscle atrophy during immobilization. We examined the effect of FOR supplementation on muscle size and strength during 2-wk of single-leg immobilization and recovery. Twenty-four healthy young men (22 ± 2 yrs; BMI = 24.3 ± 2.9 kg/m2) were randomly allocated to either a Fortetropin® supplement (FOR-SUPP, n = 12) group consuming 19.8 g/d of FOR or placebo (PLA-SUPP, n = 12) group consuming energy- and macronutrient-matched cheese powder for 6-wk. The 6-wk period consisted of 2-wk run-in, 2-wk single-leg immobilization, and 2-wk recovery phase returning to habitual physical activities. Ultrasonography, dual-energy X-ray absorptiometry, muscle biopsies and isometric peak torque assessments were performed prior to and following each phase (days 1, 14, 28, and 42) to measure vastus lateralis and muscle fiber cross-section area (CSA), leg lean mass (LM), and muscular strength. Blood samples were taken on days 1 and 42 for measurement of plasma myostatin concentration, which increased in PLA-SUPP (4221 ± 541 pg/mL to 6721 ± 864 pg/mL, P = 0.013) but not in FOR-SUPP (5487 ± 489 pg/mL to 5383 ± 781 pg/mL, P = 0.900). After the immobilization phase, vastus lateralis CSA, LM, and isometric peak torque were decreased by 7.9 ± 1.7% (P < 0.001), -1.6 ± 0.6% (P = 0.037), and -18.7 ± 2.7% (P < 0.001) respectively, with no difference between groups. The decreased peak torque was recovered after 2-wk of normal activity (vs. day 1 …

PURPOSE: To investigate the impact of endogenous (natural) and exogenous (synthetic) hormone exposure on myoblast proliferation, differentiation, and migration in C2C12 mouse myoblasts. Our secondary aim was to explore the effect of these hormones on the response to electrical pulse stimulation (EPS).METHODS: C2C12 myoblasts were cultured with the following hormones: 17β-estradiol (E2) and progesterone versus EE and first-to fourth-generation progestins [medroxyprogesterone acetate (MPA), levonorgestrel (LNG), desogestrel (DESO), and drospirenone (DRP), respectively] and were assessed for their cellular response (proliferation, differentiation, migration, protein expression) before and after EPS.RESULTS: Cell proliferation was significantly decreased with the addition of progesterone greater than 1.5 ng/ml [3 ng/ml:-18%(p< 0.001), 10 ng/ml:-17%(p< 0.001), 20 ng/ml:-22%(p< 0.001), 40 ng/ml …

ObjectiveTo determine how distinct combinations of resistance training prescription (RTx) variables (load, sets and frequency) affect muscle strength and hypertrophy.Data sourcesMEDLINE, Embase, Emcare, SPORTDiscus, CINAHL, and Web of Science were searched until February 2022.Eligibility criteriaRandomised trials that included healthy adults, compared at least 2 predefined conditions (non-exercise control (CTRL) and 12 RTx, differentiated by load, sets and/or weekly frequency), and reported muscle strength and/or hypertrophy were included.AnalysesSystematic review and Bayesian network meta-analysis methodology was used to compare RTxs and CTRL. Surface under the cumulative ranking curve values were used to rank conditions. Confidence was assessed with threshold analysis.ResultsThe strength network included 178 studies (n=5097; women=45%). The hypertrophy network included 119 …

VLCD may be a viable option in certain populations; however, priority needs to be given to resistance exercise training, and secondarily to adequate protein intake should be part of this dietary regime to mitigate losing muscle mass.

Hormonal changes around ovulation divide the menstrual cycle (MC) into the follicular and luteal phases. In addition, oral contraceptives (OCs) have active (higher hormone) and placebo phases. Although there are some MC-based effects on various physiological outcomes, we found these differences relatively subtle and difficult to attribute to specific hormones, as estrogen and progesterone fluctuate rather than operating in a complete on/off pattern as observed in cellular or preclinical models often used to substantiate human data. A broad review reveals that the differences between the follicular and luteal phases and between OC active and placebo phases are not associated with marked differences in exercise performance and appear unlikely to influence muscular hypertrophy in response to resistance exercise training. A systematic review and meta-analysis of substrate oxidation between MC phases …

BackgroundAging is the primary risk factor for sarcopenia and mobility limitations. Exercise reduces these risks, but older adults have lower levels of participation in physical activity and exercise. We investigated the preliminary effectiveness of a live, online exercise program on community-dwelling older adults' physical activity levels.MethodsA mixed-method pilot randomized controlled trial was conducted according to CONSORT 2010 statement: extension for pilot and feasibility trials. Sedentary, generally healthy older adults (65–80 years) were randomly assigned to the online exercise intervention (ACTIVE) or a waitlist control (CON) group. Outcomes were measured pre-randomization and following the 8-week intervention for ACTIVE and CON and two months following the end of the intervention for the ACTIVE group. Outcomes included habitual physical activity levels, depression, anxiety, loneliness, life-space mobility, nutrition risk, and feasibility. All participants were invited to participate post-intervention in individual semi-structured qualitative interviews. Reporting of the qualitative research followed the checklist for the Consolidated Criteria for Reporting research.ResultsSeventeen older adults (71% women) were allocated to ACTIVE group, while 15 were allocated to CON group (87% women). Following the intervention, participants in the ACTIVE group reported reduced feelings of depression and improved life-space mobility compared to waitlist control participants. The ACTIVE group had good adherence (97%) and acceptability (98%). Twenty-two participants participated in qualitative interviews. Four themes were identified, including …

The present study aimed to develop an isotope protocol to achieve equilibrium of 13CO2 in breath of cats during carbon oxidation studies using L-[1-13C]-Phenylalanine (L-[1-13C]-Phe), provided orally in repeated meals. One adult male cat was used in two experiments. In each experiment, three isotope protocols were tested in triplicate using the same cat. During carbon oxidation study days, the cat was offered thirteen small meals to achieve and maintain a physiological fed state. In experiment 1, the isotope protocols tested (A, B and C) had a similar priming dose of NaH13CO3 (0⋅176 mg/kg; offered in meal 6), but different priming [4⋅8 mg/kg (A) or 9⋅4 mg/kg (B and C); provided in meal 6] and constant [1⋅04 mg/kg (A and B) or 2⋅4 mg/kg (C); offered in meals 6–13] doses of L-[1-13C]-Phe. In experiment 2, the isotope protocols tested (D, E and F) had similar priming (4⋅8 mg/kg; provided in meal 5) and …

The definition of sarcopenia, the age-related loss of muscle mass, has evolved since the term’s inception and yet there is no consensus. Many of the identified definitions of sarcopenia centre their criteria around the loss of muscle mass, loss of function, and weakness. Common variables to various definitions of sarcopenia are appendicular lean soft tissue mass (often called muscle mass), grip strength, and gait speed. However, a lack of consensus remains among operational definitions and diagnostics for this newly recognized disease and may be attributed to the absence of appropriate tools that accurately measure the outcomes of interest, such as skeletal muscle instead of lean mass. In this narrative review, we describe the evolution of the consensus groups’ definition of sarcopenia, address the need for more accurate measures of muscle mass and function, and effective, low-cost treatments (i.e., resistance …

Sarcopenia is associated with falls, and can complicate recovery following total joint replacement (TJR) surgery. We examined (1) the prevalence of sarcopenia indicators and lower-than-recommended protein intake among TJR patients and non-TJR community participants and (2) the relationships between dietary protein intake and sarcopenia indicators. We recruited adults ≥65 years of age who were undergoing TJR, and adults from the community not undergoing TJR (controls). We assessed grip strength and appendicular lean soft-tissue mass (ALSTMBMI) using DXA, and applied the original Foundation for the National Institutes of Health Sarcopenia Project cut-points for sarcopenia indicators (grip strength <26 kg for men and <16 kg for women; ALSTM <0.789 m2 for men and <0.512 m2 for women) and less conservative cut-points (grip strength <31.83 kg for men and <19.99 kg for women; ALSTM …