A Brief Narrative Review of the Underlying Mechanisms Whereby Omega-3 Fatty Acids May Influence Skeletal Muscle: From Cell Culture to Human Interventions.

Skeletal muscle is essential for human locomotion as well as maintaining metabolic homeostasis. Age-related reduction in skeletal muscle mass, strength, and function (i.e., sarcopenia) is a result of pathophysiological processes that include inflammation, alteration of molecular signaling for muscle protein synthesis and degradation, changes in insulin sensitivity, as well as altered skeletal muscle satellite cell activity. Finding strategies to mitigate skeletal muscle loss with age is deemed paramount as the percentage of the population continues to shift towards having more older adults with sarcopenia. Recent research indicates omega-3 fatty acid supplementation can influence anabolic or catabolic pathways in skeletal muscle. Our brief review will provide a synopsis of some underlying mechanisms that may be attributed to omega-3 fatty acid supplementation's effects on skeletal muscle. We will approach this review by focusing on cell culture, animal (pre-clinical models), and human studies evaluating omega-3 fatty acid supplementation, with suggestions for future research. In older adults, omega-3 fatty acids may possess some potential to modify pathophysiological pathways associated with sarcopenia; however, it is highly likely that omega-3 fatty acids need to be combined with other anabolic interventions to effectively ameliorate sarcopenia.

Low phytic acid pea supplementation as an approach to combating iron deficiency in female runners: A randomized control trial.

Background: Iron deficiency (ID) is the most prevalent micronutrient deficiency in the world and the leading cause of anemia globally. Female athletes are at a disproportionate risk for ID due to blood loss through menstruation and decreased iron absorption secondary to exercise. Field peas are a rich source of iron but, similar to iron from other plant-based sources, the iron has limited bioavailability due to high levels of phytic acid, an inherent compound that binds to cations, creating a salt (phytate), which limits absorption during digestion. Aim: The purpose of our research was to investigate the effect of a field pea variety bred to have low levels of phytic acid on plasma ferritin, exercise performance, and body composition in female runners. Methods: Twenty-eight female runners (age:34.6 ± 9.7 years; weight: 65.1 ± 8.1 kg; VO2max: 50.7 ± 8.9 ml/kg/min) underwent measures of ferritin, exercise performance, and body composition before and after being randomly assigned to consume a powder derived from regular peas, low phytic acid peas, or a non-pea control (maltodextrin), plus vitamin C for 8 weeks. Results: The regular pea and low phytic acid pea groups had a 14.4% and 5.1% increase in plasma ferritin, respectively, while the maltodextrin group had a decrease of 2.2%; however, the difference in changes between groups was not statistically significant. No differences between groups were evident in any of the other measures. Conclusion: Larger doses or longer duration of pea supplementation may be necessary to induce meaningful changes in iron status. This trial was registered at ClinicalTrials.gov (NCT04872140).

A 2-yr Randomized Controlled Trial on Creatine Supplementation during Exercise for Postmenopausal Bone Health.

PURPOSE: Our purpose was to examine the effects of 2 yr of creatine monohydrate supplementation and exercise on bone health in postmenopausal women. METHODS: Two hundred and thirty-seven postmenopausal women (mean age, 59 yr) were randomized to receive creatine (0.14 g·kg -1 ·d -1 ) or placebo during a resistance training (3 d·wk -1 ) and walking (6 d·wk -1 ) program for 2 yr. Our primary outcome was the femoral neck bone mineral density (BMD), with lumbar spine BMD and proximal femur geometric properties as the secondary outcomes. RESULTS: Compared with placebo, creatine supplementation had no effect on BMD of the femoral neck (creatine: 0.725 ± 0.110 to 0.712 ± 0.100 g·cm -2 ; placebo: 0.721 ± 0.102 to 0.706 ± 0.097 g·cm -2 ), total hip (creatine: 0.879 ± 0.118 to 0.872 ± 0.114 g·cm -2 ; placebo: 0.881 ± 0.111 to 0.873 ± 0.109 g·cm -2 ), or lumbar spine (creatine: 0.932 ± 0.133 to 0.925 ± 0.131 g·cm -2 ; placebo: 0.923 ± 0.145 to 0.915 ± 0.143 g·cm -2 ). Creatine significantly maintained section modulus (1.35 ± 0.29 to 1.34 ± 0.26 vs 1.34 ± 0.25 to 1.28 ± 0.23 cm 3 (placebo), P = 0.0011), predictive of bone bending strength, and buckling ratio (10.8 ± 2.6 to 11.1 ± 2.2 vs 11.0 ± 2.6 to 11.6 ± 2.7 (placebo), P = 0.011), predictive of reduced cortical bending under compressive loads, at the narrow part of the femoral neck. Creatine reduced walking time over 80 m (48.6 ± 5.6 to 47.1 ± 5.4 vs 48.3 ± 4.5 to 48.2 ± 4.9 s (placebo), P = 0.0008) but had no effect on muscular strength (i.e., one-repetition maximum) during bench press (32.1 ± 12.7 to 42.6 ± 14.1 vs 30.6 ± 10.9 to 41.4 ± 14 kg (placebo)) and hack squat (57.6 ± 21.6 to 84.4 ± 28.1 vs 56.6 ± 24.0 to 82.7 ± 25.0 kg (placebo)). In the subanalysis of valid completers, creatine increased lean tissue mass compared with placebo (40.8 ± 5.7 to 43.1 ± 5.9 vs 40.4 ± 5.3 to 42.0 ± 5.2 kg (placebo), P = 0.046). CONCLUSIONS: Two years of creatine supplementation and exercise in postmenopausal women had no effect on BMD; yet, it improved some bone geometric properties at the proximal femur.

Effects of Omega-3 Supplementation Alone and Combined with Resistance Exercise on Skeletal Muscle in Older Adults: A Systematic Review and Meta-Analysis.

Sarcopenia negatively affects skeletal muscle mass and function in older adults. Omega-3 (ω-3) fatty acid supplementation, with or without resistance exercise training (RET), is suggested to play a role as a therapeutic component to prevent or treat the negative effects of sarcopenia. A systematic review and meta-analysis were conducted on the impact of ω-3 fatty acid supplementation with or without RET on measures of muscle mass and function in older adults (≥55 y). The data sources included SPORTDiscus, PubMed, and Medline. All the study types involving ω-3 fatty acid supplementation on measures of muscle mass and function in older adults (without disease) were included. The mean differences (MDs) or standardized mean differences (SMDs) with 95% confidence intervals were calculated and pooled effects assessed. Sixteen studies (1660 females, 778 males) met our inclusion criteria and were included in the meta-analysis. ω-3 fatty acid supplementation did not impact lean tissue mass (SMD 0.09 [-0.10, 0.28]). Benefits were observed for lower body strength (SMD 0.54 [0.33, 0.75]), timed-up-and-go (MD 0.29 [0.23, 0.35]s), and 30-s sit-to-stand performance (MD 1.93 [1.59, 2.26] repetitions) but not walking performance (SMD -0.01 [-0.10, 0.07]) or upper body strength (SMD 0.05 [-0.04, 0.13]). Supplementing with ω-3 fatty acids may improve the lower-body strength and functionality in older adults.

Creatine supplementation for older adults: Focus on sarcopenia, osteoporosis, frailty and Cachexia.

Sarcopenia refers to the age-related reduction in strength, muscle mass and functionality which increases the risk for falls, injuries and fractures. Sarcopenia is associated with other age-related conditions such as osteoporosis, frailty and cachexia. Identifying treatments to overcome sarcopenia and associated conditions is important from a global health perspective. There is evidence that creatine monohydrate supplementation, primarily when combined with resistance training, has favorable effects on indices of aging muscle and bone. These musculoskeletal benefits provide some rationale for creatine being a potential intervention for treating frailty and cachexia. The purposes of this narrative review are to update the collective body of research pertaining to the effects of creatine supplementation on indices of aging muscle and bone (including bone turnover markers) and present possible justification and rationale for its utilization in the treatment of frailty and cachexia in older adults.

Benefits of a plant-based diet and considerations for the athlete.

Individuals may opt to follow a plant-based diet for a variety of reasons, such as religious practices, health benefits or concerns for animal or environmental welfare. Such diets offer a broad spectrum of health benefits including aiding in the prevention and management of chronic diseases. In addition to health benefits, a plant-based diet may provide performance-enhancing effects for various types of exercise due to high carbohydrate levels and the high concentration of antioxidants and phytochemicals found in a plant-based diet. However, some plant-based foods also contain anti-nutrional factors, such as phytate and tannins, which decrease the bioavailability of key nutrients, such as iron, zinc, and protein. Thus, plant-based diets must be carefully planned to ensure adequate intake and absorption of energy and all essential nutrients. The current narrative review summarizes the current state of the research concerning the implications of a plant-based diet for health and exercise performance. It also outlines strategies to enhance the bioavailability of nutrients, sources of hard-to-get nutrients, and sport supplements that could interest plant-based athletes.

The impact of the COVID-19 pandemic on the diet, training habits and fitness of Masters cyclists.

Background: The number of Masters-level athletes (≥ 35 years of age) taking part in cycling has increased in the past years which may have beneficial effects on their health. The restrictions brought on by the COVID-19 pandemic has the potential to negatively impact the diet, training and fitness of these individuals due to restrictions in place to slow the spread of the virus. Aim: To investigate how the COVID-19 pandemic impacted the diet, training and fitness of Masters-level cyclists. Methods: 32 Masters cyclists (12 males, 20 females; mean age 47 ± 10 years) completed two incremental exercise tests one month apart during the pandemic to assess sport-specific fitness. Participants also completed online questionnaires to report their sedentary behavior and dietary intake before and during the pandemic, and their training volume and intensity for a specified week in February (before the pandemic) and each of March, April and May (during the pandemic). Results: No differences were seen in fitness (p = 0.6), training volume (p = 0.24) or intensity (p = 0.79) and sedentary behavior (p = 0.14) during the pandemic. Energy intake was unchanged (p = 1.0) during the pandemic, but participants consumed lower amounts of key nutrients such as fiber, vitamin A, omega-3 fatty acids and potassium (p < 0.05) while consuming more alcohol (p = 0.008) and vitamin C (p = 0.03). Conclusions: Our data shows that the COVID-19 pandemic has undesirable effects on nutrient and alcohol intake of Masters cyclists without impacting their training regimes, which may have adverse effects on their overall health and fitness in the long term.

Effect of yoga on health-related outcomes in people at risk of fractures: a systematic review.

We summarized the effects of yoga on health-related outcomes and adverse events in men and postmenopausal women ≥50 years-old at increased risk of fracture, to inform the updated Osteoporosis Canada clinical practice guidelines. Six databases were searched for observational studies, randomized controlled trials and case series. Certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation handbook. Nine studies were included and reported using narrative syntheses due to the limited available evidence. Overall, the available evidence was of very low certainty. There was no effect of yoga on health-related quality of life in randomized trials. Effects on other health-related outcomes were mixed or not available in the literature. Five studies reported no adverse events directly related to the study intervention, and 2 studies did not report whether adverse events occurred. However, 2 case series reported vertebral fractures related to yoga participation, possibly due to excessive spinal flexion. Due to the limited and very low certainty evidence, guideline developers will need to draw indirect evidence from yoga studies among middle aged or older adults that are not at fracture risk. PROSPERO: CRD42019124898. Novelty: Evidence in general was of very low certainty. Yoga had no effect on health-related quality of life in randomized trials. Evidence was mixed or unavailable for other outcomes. Case studies reported yoga poses involving spinal flexion coincided with incidents of vertebral compression fracture among older adults with increased fracture risk.

Dietary Supplementation for Para-Athletes: A Systematic Review.

The use of dietary supplements is high among athletes and non-athletes alike, as well as able-bodied individuals and those with impairments. However, evidence is lacking in the use of dietary supplements for sport performance in a para-athlete population (e.g., those training for the Paralympics or similar competition). Our objective was to examine the literature regarding evidence for various sport supplements in a para-athlete population. A comprehensive literature search was conducted using PubMed, SPORTDiscus, MedLine, and Rehabilitation and Sports Medicine Source. Fifteen studies met our inclusion criteria and were included in our review. Seven varieties of supplements were investigated in the studies reviewed, including caffeine, creatine, buffering agents, fish oil, leucine, and vitamin D. The evidence for each of these supplements remains inconclusive, with varying results between studies. Limitations of research in this area include the heterogeneity of the subjects within the population regarding functionality and impairment. Very few studies included individuals with impairments other than spinal cord injury. Overall, more research is needed to strengthen the evidence for or against supplement use in para-athletes. Future research is also recommended on performance in para-athlete populations with classifiable impairments other than spinal cord injuries.

Meta-Analysis Examining the Importance of Creatine Ingestion Strategies on Lean Tissue Mass and Strength in Older Adults.

Creatine supplementation in conjunction with resistance training (RT) augments gains in lean tissue mass and strength in aging adults; however, there is a large amount of heterogeneity between individual studies that may be related to creatine ingestion strategies. Therefore, the purpose of this review was to (1) perform updated meta-analyses comparing creatine vs. placebo (independent of dosage and frequency of ingestion) during a resistance training program on measures of lean tissue mass and strength, (2) perform meta-analyses examining the effects of different creatine dosing strategies (lower: ≤5 g/day and higher: >5 g/day), with and without a creatine-loading phase (≥20 g/day for 5-7 days), and (3) perform meta-analyses determining whether creatine supplementation only on resistance training days influences measures of lean tissue mass and strength. Overall, creatine (independent of dosing strategy) augments lean tissue mass and strength increase from RT vs. placebo. Subanalyses showed that creatine-loading followed by lower-dose creatine (≤5 g/day) increased chest press strength vs. placebo. Higher-dose creatine (>5 g/day), with and without a creatine-loading phase, produced significant gains in leg press strength vs. placebo. However, when studies involving a creatine-loading phase were excluded from the analyses, creatine had no greater effect on chest press or leg press strength vs. placebo. Finally, creatine supplementation only on resistance training days significantly increased measures of lean tissue mass and strength vs. placebo.

Efficacy of Creatine Supplementation and Resistance Training on Area and Density of Bone and Muscle in Older Adults.

PURPOSE: To examine the efficacy of creatine (Cr) supplementation and any sex differences during supervised whole-body resistance training (RT) on properties of bone and muscle in older adults. METHODS: Seventy participants (39 men, 31 women; mean age ± standard deviation: 58 ± 6 yr) were randomized to supplement with Cr (0.1 g·kg-1·d-1) or placebo (Pl) during RT (3 d·wk-1 for 1 yr). Bone geometry (radius and tibia) and muscle area and density (forearm and lower leg) were assessed using peripheral quantitative computed tomography. RESULTS: Compared with Pl, Cr increased or maintained total bone area in the distal tibia (Cr, Δ +17 ± 27 mm2; Pl, Δ -1 ± 22 mm2; P = 0.031) and tibial shaft (Cr, Δ 0 ± 9 mm2; Pl, Δ -5 ± 7 mm2; P = 0.032). Men on Cr increased trabecular (Δ +28 ± 31 mm2; P < 0.001) and cortical bone areas in the tibia (Δ +4 ± 4 mm2; P < 0.05), whereas men on Pl increased trabecular bone density (Δ +2 ± 2 mg·cm-3; P < 0.01). There were no bone changes in the radius (P > 0.05). Cr increased lower leg muscle density (Δ +0.83 ± 1.15 mg·cm-3; P = 0.016) compared with Pl (Δ -0.16 ± 1.56 mg·cm-3), with no changes in the forearm muscle. CONCLUSIONS: One year of Cr supplementation and RT had some favorable effects on measures of bone area and muscle density in older adults.

The effect of omega3 fatty acid supplementation on PPARγ and UCP2 expressions, resting energy expenditure, and appetite in athletes.

BACKGROUND: Omega3 fatty acids as a ligand of energy-related genes, have a role in metabolism, and energy expenditure. These effects are due to changes in the expression of peroxisome proliferator-activated receptor-gamma (PPARγ) and uncoupling protein2 (UCP2). This study evaluated the effect of omega3 supplements on PPARγ mRNA expression and UCP2 mRNA expression and protein levels, as regulators of energy metabolism, resting energy expenditure (REE), and appetite in athletes. METHODS: In a 3-week double-blind RCT in Tabriz, Iran, in 2019, 36 male athletes, age 21.86 (±3.15) y with 16.17 (±5.96)% body fat were randomized to either an intervention (2000 mg/day omega3; EPA: 360, DHA: 240) or placebo (2000 mg/day edible paraffin) groups. Appetite and REE were assessed before and after the intervention. PPARγ and UCP2 mRNA expression and UCP2 protein levels in blood were evaluated by standard methods. RESULTS: Results showed PPARγ mRNA levels, and UCP2 mRNA and protein levels increased in omega3 group (p < 0.05), as did REE (p < 0.05). Also, differences in the sensation of hunger or satiety were significant (p < 0.05). CONCLUSIONS: Our findings showed that omega3 supplementation leads to the up-regulation of PPARγ and UCP2 expressions as the indicators of metabolism in healthy athletes.

Effect of 12 months of creatine supplementation and whole-body resistance training on measures of bone, muscle and strength in older males.

BACKGROUND: The combination of creatine supplementation and resistance training (10-12 weeks) has been shown to increase bone mineral content and reduce a urinary indicator of bone resorption in older males compared with placebo. However, the longer-term effects (12 months) of creatine and resistance training on bone mineral density and bone geometric properties in older males is unknown. AIM: To assess the effects of 12 months of creatine supplementation and supervised, whole-body resistance training on bone mineral density, bone geometric properties, muscle accretion, and strength in older males. METHODS: Participants were randomized to supplement with creatine (n = 18, 49-69 years, 0.1 g·kg-1·d-1) or placebo (n = 20, 49-67 years, 0.1 g·kg-1·d-1) during 12 months of supervised, whole-body resistance training. RESULTS: After 12 months of training, both groups experienced similar changes in bone mineral density and geometry, bone speed of sound, lean tissue and fat mass, muscle thickness, and muscle strength. There was a trend (p = 0.061) for creatine to increase the section modulus of the narrow part of the femoral neck, an indicator of bone bending strength, compared with placebo. Adverse events did not differ between creatine and placebo. CONCLUSIONS: Twelve months of creatine supplementation and supervised, whole-body resistance training had no greater effect on measures of bone, muscle, or strength in older males compared with placebo.

Nutritional interventions during bed rest and spaceflight: prevention of muscle mass and strength loss, bone resorption, glucose intolerance, and cardiovascular problems.

Bed rest is necessary for many medical conditions but also used as a ground-based model for space flight (along with head-down tilt to simulate fluid shifts in microgravity). The purpose of this review is to examine nutritional interventions during bed rest and spaceflight for prevention of muscle and strength loss, glucose intolerance, bone resorption, and cardiovascular problems. Increased dietary protein intake and supplementation with amino acids, ß-hydroxy-ß-methylbutyrate, or cofactors with antioxidant properties are effective for ameliorating bed rest-induced loss of muscle mass and strength. Previous literature involving bed rest with dietary protein/amino acid supplementation had mixed findings, likely due to differences in dosage. Although high protein intake in some studies prevents bed rest-induced muscle loss, it also increases bone resorption. High calcium intake and vitamin D supplementation are not beneficial for preventing bone degradation during bed rest or spaceflight. Very few studies investigated countermeasures to prevent glucose intolerance and cardiovascular risks during bed rest/spaceflight. Low-glycemic index diets might be beneficial for the prevention of bed rest-induced glucose intolerance and cardiovascular problems. The present evidence warrants additional studies on the exact threshold of protein/amino acid intake to prevent the loss of muscle mass and strength during bed rest/spaceflight specifically to maintain the beneficial effects of proteins on muscle mass and function without increasing bone resorption. Furthermore, it is suggested to study the effects of vitamin K supplementation on bone health during bed rest/spaceflight and determine the role of long-term low-glycemic index diets on glucose regulation and cardiovascular health during extended bed rest.

Benefits of Creatine Supplementation for Vegetarians Compared to Omnivorous Athletes: A Systematic Review.

BACKGROUND: Creatine monohydrate is a nutritional supplement often consumed by athletes in anaerobic sports. Creatine is naturally found in most meat products; therefore, vegetarians have reduced creatine stores and may benefit from supplementation. OBJECTIVE: to determine the effects of creatine supplementation on vegetarians. DATA SOURCES: PubMed and SPORTDiscus. Eligibility criteria: Randomized controlled trials (parallel group, cross-over studies) or prospective studies. PARTICIPANTS: Vegetarians. INTERVENTION: Creatine supplementation. Study appraisal and synthesis: A total of 64 records were identified, and eleven full-text articles (covering nine studies) were included in this systematic review. RESULTS: Creatine supplementation in vegetarians increased total creatine, creatine, and phosphocreatine concentrations in vastus lateralis and gastrocnemius muscle, plasma, and red blood cells, often to levels greater than omnivores. Creatine supplementation had no effect on brain levels of phosphocreatine. Creatine supplementation increased lean tissue mass, type II fiber area, insulin-like growth factor-1, muscular strength, muscular endurance, Wingate mean power output, and brain function (memory and intelligence) in vegetarian participants. Studies were mixed on whether creatine supplementation improved exercise performance in vegetarians to a greater extent compared to omnivores. LIMITATIONS: Studies that were reviewed had moderate-high risk of bias. CONCLUSIONS: Overall, it appears vegetarian athletes are likely to benefit from creatine supplementation.

Variables Influencing the Effectiveness of Creatine Supplementation as a Therapeutic Intervention for Sarcopenia.

Sarcopenia is an age-related muscle condition characterized by a reduction in muscle quantity, force generating capacity and physical performance. Sarcopenia occurs in 8-13% of adults ≥ 60 years of age and can lead to disability, frailty, and various other diseases. Over the past few decades, several leading research groups have focused their efforts on developing strategies and recommendations for attenuating sarcopenia. One potential nutritional intervention for sarcopenia is creatine supplementation. However, research is inconsistent regarding the effectiveness of creatine on aging muscle. The purpose of this perspective paper is to: (1) propose possible reasons for the inconsistent responsiveness to creatine in aging adults, (2) discuss the potential mechanistic actions of creatine on muscle biology, (3) determine whether the timing of creatine supplementation influences aging muscle, (4) evaluate the evidence investigating the effects of creatine with other compounds (protein, conjugated linoleic acid) in aging adults, and (5) provide insight regarding the safety of creatine for aging adults.

Effectiveness of Creatine Supplementation on Aging Muscle and Bone: Focus on Falls Prevention and Inflammation.

Sarcopenia, defined as the age-related decrease in muscle mass, strength and physical performance, is associated with reduced bone mass and elevated low-grade inflammation. From a healthy aging perspective, interventions which overcome sarcopenia are clinically relevant. Accumulating evidence suggests that exogenous creatine supplementation has the potential to increase aging muscle mass, muscle performance, and decrease the risk of falls and possibly attenuate inflammation and loss of bone mineral. Therefore, the purpose of this review is to: (1) summarize the effects of creatine supplementation, with and without resistance training, in aging adults and discuss possible mechanisms of action, (2) examine the effects of creatine on bone biology and risk of falls, (3) evaluate the potential anti-inflammatory effects of creatine and (4) determine the safety of creatine supplementation in aging adults.

Research in nutritional supplements and nutraceuticals for health, physical activity, and performance: moving forward 1.

This Horizons is part of a series that identifies key, forward-thinking research questions and challenges that need to be addressed. Specifically, this Horizons paper discusses research in nutritional supplements and nutraceuticals for health, physical activity, and performance, and is the product of a discussion by an expert panel that took place in January 2018 prior to the Canadian Nutrition Society Thematic Conference "Advances in Sport Nutrition from Daily Living to High Performance Sport". The objective of this Horizons paper was to identify core considerations for future studies for this research area, and how scientists can be leaders in the field to ensure the best quality science is available for decision makers. It is strongly recommended that the various elements highlighted throughout this Horizons paper will increase the awareness of the significant before-, during-, and after-research due-diligence required to produce research of the highest quality. While it is recognized that many scientists will not be able to meet all of these aspects, it is nonetheless important to consider the points outlined and to recognize that those elements that are not met in studies may be significant limitations. Highlights Research questions that are hypothesis-driven are the strongest, and when combined with careful planning of the study, the result will often be of the best quality. Studies with a strong experimental design help discern between evidence-based findings and those that have not been substantiated.

Creatine monohydrate supplementation during eight weeks of progressive resistance training increases strength in as little as two weeks without reducing markers of muscle damage.

BACKGROUND: Creatine supplementation (Cr) increases strength during resistance training, but the time course of this strength increase is unclear. The aim was to determine the precise time course by which Cr could increase strength and whether Cr prevents muscle damage during eight weeks of resistance training. METHODS: Young males were randomized (double blind) to Cr (N.=9, 0.07g/kg/d) and placebo (N.=9) during 8-weeks of resistance training (3 d/week). Strength was assessed across six exercises every two weeks. Venous blood samples obtained at baseline, and 24 and 48 hours after the final resistance training session were assessed for creatine kinase [CK] and lactate dehydrogenase [LDH] as measures of muscle damage. RESULTS: Strength was significantly higher in the Cr versus placebo group (P<0.05) after two weeks of training for three of the six exercises (bench press, leg press, shoulder press). By the end of the eight weeks of training, strength was significantly higher in the Cr versus placebo group (P<0.05) for four of the six exercises (bench press, leg press, shoulder press, and triceps extension, but not biceps curl or lat-pulldown). Creatine supplementation did not prevent muscle damage. Indeed, muscle damage markers increased in the Cr compared to placebo group (P<0.05). CONCLUSIONS: Cr increased muscular strength in as little as two weeks during a resistance training program; however, this was not accompanied by decreased muscle damage. Greater muscle damage with Cr may be due to a greater training intensity enabled by Cr supplementation. This might lead to greater protein turnover and enhanced muscle adaptation.

Creatine Supplementation During Resistance Training Does Not Lead to Greater Bone Mineral Density in Older Humans: A Brief Meta-Analysis.

Creatine supplementation during resistance training has potential beneficial effects on properties of bone in aging adults. We systematically reviewed randomized controlled trials (RCTs) investigating the effect of creatine supplementation combined with resistance training on bone mineral density (BMD) in aging adults. We searched PubMed and SPORTDiscus databases and included RCTs of ≥3 months duration that examined the combined effect of creatine and resistance training on bone mineral in adults >50 years of age or postmenopausal. Meta-analyses were performed when applicable trials were available on whole body and clinically important bone sites. Five trials met inclusion criteria with a total of 193 participants. Two of the studies reported significant benefits of creatine supplementation and resistance training compared to resistance training alone on bone. Meta-analyses revealed no greater effect of creatine and resistance training compared to resistance training alone on whole body BMD (MD: 0.00, 95% CI -0.01 to 0.01, p = 0.50), hip BMD (MD -0.01, 95% CI -0.02 to 0.01, p = 0.26), femoral neck BMD (MD 0.00, 95% CI -0.01 to 0.01, p = 0.71), and lumbar spine BMD (MD 0.01, 95% CI -0.01 to 0.03, p = 0.32). In conclusion, there is a limited number of RCTs examining the effects of creatine supplementation and resistance training on BMD in older adults. Our meta-analyses revealed no significant effect on whole body, hip, femoral neck, or lumbar spine BMD when comparing creatine and resistance training to resistance training alone. Future longer term (>12 month) trials with higher resistance training frequencies (≥3 times per week) is warranted.