Daily L-leucine supplementation in novice trainees during a 12-week weight training program.

PURPOSE: To investigate the effects of daily oral L-leucine ingestion on strength, bone mineral-free lean tissue mass (LTM) and fat mass (FM) of free living humans during a 12-wk resistance-training program. METHODS: Twenty-six initially untrained men (n = 13 per group) ingested either 4 g/d of L-leucine (leucine group: age 28.5 ± 8.2 y, body mass index 24.9 ± 4.2 kg/m2) or a corresponding amount of lactose (placebo group: age 28.2 ± 7.3 y, body mass index 24.9 ± 4.2 kg/m2). All participants trained under supervision twice per week following a prescribed resistance training program using eight standard exercise machines. Testing took place at baseline and at the end of the supplementation period. Strength on each exercise was assessed by five repetition maximum (5-RM), and body composition was assessed by dual energy X-ray absorptiometry (DXA). RESULTS: The leucine group demonstrated significantly higher gains in total 5-RM strength (sum of 5-RM in eight exercises) and 5-RM strength in five out of the eight exercises (P < .05). The percentage total 5-RM strength gains were 40.8% (± 7.8) and 31.0% (± 4.6) for the leucine and placebo groups respectively. Significant differences did not exist between groups in either total percentage LTM gains or total percentage FM losses (LTM: 2.9% ± 2.5 vs 2.0% ± 2.1, FM: 1.6% ± 15.6 vs 1.1% ± 7.6). CONCLUSION: These results suggest that 4 g/d of L-leucine supplementation may be used as a nutritional supplement to enhance strength performance during a 12-week resistance training program of initially untrained male participants

Validity of Telemetric-Derived Measures of Heart Rate Variability : A Systematic Review

Validity of Telemetric-Derived Measures of Heart Rate Variability: A Systematic Review. JEPonline 2016;19(6):64-84. Heart rate variability (HRV) is a widely accepted indirect measure of autonomic function with widespread application across many settings. Although traditionally measured from the ‘gold standard’ criterion electrocardiography (ECG), the development of wireless telemetric heart rate monitors (HRMs) extends the scope of the HRV measurement. However, the validity of telemetric-derived data against the criterion ECG data is unclear. Thus, the purpose of this study was twofold: (a) to systematically review the validity of telemetric HRM devices to detect inter-beat intervals and aberrant beats; and (b) to determine the accuracy of HRV parameters computed from HRM-derived inter-beat interval time series data against criterion ECG-derived data in healthy adults aged 19 to 62 yrs. A systematic review of research evidence was conducted. Four electronic databases were accessed to obtain relevant articles (PubMed, EMBASE, MEDLINE and SPORTDiscus. Articles published in English between 1996 and 2016 were eligible for inclusion. Outcome measures included temporal and power spectral indices (Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology (1996). The review confirmed that modern HRMs (Polar® V800™ and Polar® RS800CX™) accurately detected inter-beat interval time-series data. The HRV parameters computed from the HRM-derived time series data were interchangeable with the ECG-derived data. The accuracy of the automatic in-built manufacturer error detection and the HRV algorithms were not established. Notwithstanding acknowledged limitations (a single reviewer, language bias, and the restricted selection of HRV parameters), we conclude that the modern Polar® HRMs offer a valid useful alternative to the ECG for the acquisition of inter-beat interval time series data, and the HRV parameters computed from Polar® HRM-derived inter-beat interval time series data accurately reflect ECG-derived HRV metrics, when inter-beat interval data are processed and analyzed using identical protocols, validated algorithms and software, particularly under controlled and stable conditions

Strength of the dominant upper and lower extremities predicts skeletal muscle mass irrespective of age and gender

Background: Sarcopenia is characterised by losses in muscle mass, strength and function. It is a contributing factor to numerous non-communicable diseases and frailty. Screening for sarcopenia typically requires measurements of handgrip strength, functional performance, and skeletal muscle mass. However, available tools do not tend to measure strength of the lower extremities. The aim of this study was to investigate associations between these measures and lower extremity strength with skeletal muscle mass in healthy young and older adults. Methods: Fifty younger (mean ± SD age = 22.7 ± 5.4 years) and 50 older (age = 69.9 ± 4.3 years) individuals received the following measurements after an overnight fast: Skeletal Muscle Index (SMI) derived by dual-energy X-ray absorptiometry, gait speed, handgrip strength (HGS), and unilateral one-repetition maximum (1RM) leg extension strength. Muscle quality (MQ), was also determined as the ratio of grip strength to appendicular lean mass of the upper body. Results: One older female and one older male were pre-sarcopenic and sarcopenic. Upper extremity MQ was below established cutpoints in 21 older participants. SMI was positively associated with upper and lower extremity strength in all groups except older men, and negatively associated with upper extremity MQ in young males. By multiple regression analysis, dominant HGS and dominant leg extension 1RM strength predicted SMI in the complete sample, accounting for 70.3% of the variance (B = 0.469 and 0.421, respectively; P < 0.00001). The equation for SMI is as follows: 4.568 + 0.025 x dominant leg extension 1RM + 0.059 x dominant grip strength. Discussion: Since muscle mass is the foremost variable in determining sarcopenia, we support the inclusion of lower extremity strength testing in addition to that of handgrip strength to enable better prediction of SMI in both older and younger individuals. MQ determination is also recommended since established algorithms may fail to identify individuals with muscle weakness

The impact of repetition mechanics on the adaptations resulting from strength-, hypertrophy- and cluster-type resistance training

Purpose: The purpose of this study was to examine the acute and chronic training responses to strength-, hypertrophy- and cluster-type resistance training. Methods: Thirty four trained males were assigned to a strength (STR: 4 x 6 repetitions, 85% of one repetition maximum, [1RM], 900s total rest), hypertrophy (HYP: 5 x 10 repetitions, 70% 1RM, 360s total rest), cluster 1 (CL-1: 4 x 6/1 repetitions, 85% 1RM, 1400s total rest), and cluster 2 (CL-2: 4 x 6/1 repetitions, 90% 1RM, 1400s total rest) regimens which were performed twice weekly for a 6 week period. Measurements were taken before, during and following the four workouts to investigate the acute training stimulus, whilst similar measurements were employed to examine the training effects before and after the intervention. Results: The improvements in 1RM strength were significantly greater for the STR (12.09 ± 2.75%; p<0.05, d=1.106) and CL-2 (13.20 ± 2.18%; p<0.001, d=0.816) regimens than the HYP regimen (8.13 ± 2.54%, d=0.453). In terms of the acute responses, the STR and CL-2 workouts resulted in greater time under tension (TUT) and impulse generation in individual repetitions than the HYP workout (p<0.05). Furthermore, the STR (+3.65 ± 2.54mmol/L-1) and HYP (+6.02 ± 2.97mmol/L-1) workouts resulted in significantly greater elevations in blood lactate concentration (p<0.001) than the CL-1 and CL-2 workouts. Conclusion: CL regimens produced similar strength improvements to STR regimens even when volume-load was elevated (CL-2). The effectiveness of the STR and CL-2 regimens underlines the importance of high loads and impulse generation for strength development

Pilot Study investigating the Impact of Serial ingestion or Co-ingestion of Creatine and Sodium bicarbonate on Performance Following Completion of a Hypertrophy Type Resistance Exercise Workout.

Purpose: To examine the ergogenic potential of creatine (Cr), sodium bicarbonate (SB),and Cr+SBafter completion of a resistance exercise bout (REB).Methods: Following recruitment,27trained males (26.8±5.7 years old) completed a one repetition maximum strength (1RM) test in the parallel squat (120.9±28.2kg). Participants then followed a standardised meal plan for 4 days whilst ingesting one of 4 supplements, and on day 5 they undertook the REB. This was a double blind randomised placebo-controlled study where participants ingested one of the following: Placebo (PLA, n=7), Cr (20g/d-1& PLA, n=8), SB (0.5 g/kg-1/d-1&PLA, n=6), andCr+SB (5 g/d-1 of Cr & 0.5 g/kg-1/d-1 SB, n=6) divided in 4 doses. The REB consisted of 4x10 repetitions (70% of 1RM, 1½ min recovery). The primary performance outcome was a 5th set (70% of 1RM) performed to volitional exhaustion.Blood glucose and lactate, heart rate, ratings of perceived exertion, sickness and stomachache scales, and time to complete each set were also recorded.Results:Participants in Cr, SB, and Cr+SB completed the required number of repetitions at 70% of 1RM however in PLA they completed the same repetitions at lower intensity (68+3.4%). Participants in PLA, Cr, SB, and Cr+SB completed 8(±1.6), 11(±5.5), 9(±3.7), and 11(±3.3) repetitions respectively during the 5th set. Despite the fact that no significant differences were observed in performance, small (SB: 0.4) and moderate effect (Cr: 0.7; Cr+SB: 1.0) sizes were observed in relation to PLA. Body mass increasedsignificantly after Cr (78.1±8.9 kg pre vs 79.1±8.9 kg post, p<0.05). No other significant differences existed in recorded variables.Conclusions: Performance gains were of higher magnitude in the Cr+SB and Cr groups. Co-ingestion of a small amount of Cr (5 g/d-1) with a standard dose ofSB (0.5 g/kg-1/d-1)appears to be equally beneficial asingestion of a standard dose of Cr (20 g/d-1). The Cr+SB was not associated with significant gains in body mass which may be beneficial in sports where size gains may negate performance. Further research is required, with larger sample size, and specific athletic populations in order to confirm the findings of the current study

Diet, functional performance and muscle quality of independent-living men and women aged 65-75 years

Age-related sarcopenia is a syndrome characterised by progressive decline in skeletal muscle mass and strength (von Haehling, Morley, & Anker, 2010). The European Working Group on Sarcopenia in Older People recommends the measurement of muscle mass and function as means of diagnosing sarcopenia (Cruz-Jentoft et al., 2010) since sole focus on measurement of muscle mass may be of limited value. The age-associated loss of muscle strength (Dynapenia) cannot be only explained by reductions in muscle size since reductions in strength are more rapid than reductions in muscle (Clark & Manini, 2012). Cawthon et al. (2014) developed cut points for appendicular lean mass (ALM) that would identify individuals with clinically significant weakness taking into account both ALM and strength. Since sarcopenia is a multifaceted syndrome with potentially modifiable factors such as dietary intakes, the aim of this pilot study was to explore the interrelationships between dietary intakes, ALM, and strength. Twenty-five healthy older adults including both female (n=15, age: 68.8 ± 2.9 years) and male (n =10, age 69.5 ± 2.5 years) participants completed a 7-day diet diary before having their handgrip strength and body composition (dual energy X-ray absorptiometry) measured. Males with ALM<19.75 kg and females with ALM<15.02 kg were defined as having low lean muscle mass, whilst cut points of <30 kg and <20 kg (Campbell & Vallis, 2014) were used to identify males and females with low strength. Participants received guidance on recording food and drink by household measures. Energy expenditure was calculated using the World Health Organization/Food and Agriculture Organization equation (Frankenfield, Roth-Yousey, & Compher, 2005) for resting energy expenditure and an activity factor of 1.5. Forty percent (40%) of the females displayed low muscle strength while their male counterparts were all above the 30 kg cut point. ALM was 25.6±3.7 and 15.9±1.7 kg for males and females respectively. Twenty-seven percent (27%) of the females were below the cut point for low lean mass whilst males were all above the equivalent cut point. Energy intake (EI) was 1753±366 kcal for males and 1376±270 kcal for females corresponding to an EI deficit of 27.8±21.7 % and 27.7±6 % for males and females respectively. EI was significantly (P<0.05) lower than recommended EI. Protein intake was 0.97±0.3 g·kg·d-1 for the males and 0.95±0.2 g·kg·d-1 for the females representing 18.8±3.1 and 17.8±2.4 % of EI for males and females respectively. Our findings suggest that females in early retirement years are at greater risk of sarcopenia and dynapenia than their male counterparts. Inadequate energy intake and protein consumption which was below current research led recommendations of 20 % suggest that females may benefit from dietary interventions that would address energy and protein deficits. References Campbell, T. M., & Vallis, L. A. (2014). Predicting fat-free mass index and sarcopenia in assisted-living older adults. Age (Dordr), 36(4), 9674. doi: 10.1007/s11357-014-9674-8 Cawthon, P. M., Peters, K. W., Shardell, M. D., McLean, R. R., Dam, T.-T. L., Kenny, A. M., . . . Guralnik, J. M. (2014). Cutpoints for low appendicular lean mass that identify older adults with clinically significant weakness. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 69(5), 567-575. Clark, B. C., & Manini, T. M. (2012). What is dynapenia? Nutrition, 28(5), 495-503. doi: 10.1016/j.nut.2011.12.002 Cruz-Jentoft, A. J., Baeyens, J. P., Bauer, J. M., Boirie, Y., Cederholm, T., Landi, F., . . . European Working Group on Sarcopenia in Older, P. (2010). Sarcopenia: European consensus on definition and diagnosis: Report of the European Working Group on Sarcopenia in Older People. Age Ageing, 39(4), 412-423. doi: 10.1093/ageing/afq034 Frankenfield, D., Roth-Yousey, L., & Compher, C. (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc, 105(5), 775-789. doi: 10.1016/j.jada.2005.02.005 Morley, J. E. (2008). Sarcopenia: diagnosis and treatment. J Nutr Health Aging, 12(7), 452-456. von Haehling, S., Morley, J. E., & Anker, S. D. (2010). An overview of sarcopenia: facts and numbers on prevalence and clinical impact. J Cachexia Sarcopenia Muscle, 1(2), 129-133. doi: 10.1007/s13539-010-0014-