Nutrition and health

Objectives:
Is there a difference between high-load (≥70 of 1RM) and low-load (70 of 1RM) resistance training (RT) on femoral neck and lumbar spine bone mineral density (BMD) in middle-aged and older people?

Study design:
This review article included 6 RCTs.

Results and conclusions:
The investigators found the meta-analysis revealed no difference in femoral neck bone mineral density [MD = 0.00 g/cm², 95% CI = -0.01 to 0.01, p = 0.63, I2 = 47%, p = 0.07] and lumbar spine bone mineral density [MD = 0.01 g/cm², 95% CI = -0.00 to 0.02, p = 0.12, I2 = 59%, p = 0.02] between high-load (≥70 of 1RM) resistance training group and low-load (70 of 1RM) resistance training group. 

The investigators found subgroup analysis revealed a significant effect of high-load resistance training on femoral neck bone mineral density when participants presented normal bone mineral density values [MD = 0.01 g/cm², 95% CI = 0.00 to 0.02, p = 0.04] and on interventions lasting up to 6 months [MD = 0.01 g/cm², 95% CI = 0.00 to 0.02, p = 0.03].

The investigators concluded both high-load (≥70 of 1RM) and low-load (70 of 1RM) resistance training (RT) have similar effects on femoral neck and lumbar spine bone mineral density (BMD) in middle-aged and older people.

Original title:
High and Low-Load Resistance Training Produce Similar Effects on Bone Mineral Density of Middle-Aged and Older People: A Systematic Review With Meta-Analysis of Randomized Clinical Trials by Souza D, Barbalho M, […], Gentil P.

Link:
https://www.sciencedirect.com/science/article/abs/pii/S0531556520303211?via%3Dihub

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Objectives:
Nitric oxide related ergogenic aids such as arginine (Arg) have shown to impact positively on sport performance through several physiological and metabolic mechanisms. However, research results have shown to be controversial. Therefore, this review article has been conducted.

Do both acute and chronic arginine supplementation increase aerobic (≤VO2max) and anaerobic (>VO2max) performance?

Study design:
This review article included 15 RCTs with 386 males and 8 females.

Arginine supplementation was ingested by participants in both acute and chronic protocols.
Acute arginine protocol was 0.15 g/kg (≈10-11 g) ingested between 60-90 minutes before physical exercises.

Chronic arginine protocol was 1.5-2 g/day during 4-7 weeks or 10-12 g/day during 8 weeks.

Random effects model and pooled standardized mean differences (SMD) were used according to Hedges’ g.

Egger’s analyses did not find publication bias in anaerobic performance [z = 0.786, p = 0.432]. However, funnel plot showed publication bias in aerobic performance data [z = 2.873, p 0.05].

Results and conclusions:
The investigators found both acute and chronic arginine supplementation significantly improved anaerobic performance [SMD = 0.24, 95% CI = 0.05 to 0.43, p = 0.01, I2 = 0%, p = 0.85].

The investigators found both acute and chronic arginine supplementation significantly improved aerobic performance [SMD = 0.84, 95% CI = 0.12 to 1.56, p = 0.02, I2 = 89%, p 0.001].

The investigators concluded both acute and chronic arginine supplementation improve (anaerobic/aerobic) performance.

Original title:
Effects of Arginine Supplementation on Athletic Performance Based on Energy Metabolism: A Systematic Review and Meta-Analysis by Viribay A, Burgos J, […], Mielgo-Ayuso J.

Link:
https://www.mdpi.com/2072-6643/12/5/1300/htm

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Objectives:
Does protein supplementation yield beneficial effects on body composition and muscle function (strength and synthesis) in healthy adults, with an emphasis on the timing of protein intake?

Study design:
This review article included 65 RCTs with 2,907 participants (1,514 men and 1,380 women, 13 unknown sex). 26, 8 and 24 studies were used for meta-analysis on lean body mass, handgrip strength and leg press strength, respectively.

Results and conclusions:
The investigators found protein supplementation was effective in improving lean body mass (LBM) in adults [MD = 0.62 kg, 95% CI = 0.36 to 0.88] and older adults [MD = 0.46 kg, 95% CI = 0.23 to 0.70].
Sensitivity analyses removing studies without exercise training had no impact on the outcome.

The investigators found no association between protein supplementation and handgrip strength [older adults: MD = 0.26 kg, 95% CI = -0.51 to 1.04] and leg press strength [adults: MD = 5.80 kg, 95% CI = -0.33 to 11.93 and older adults: MD = 1.97 kg, 95% CI = -2.78 to 6.72].
Sensitivity analyses removing studies without exercise training had no impact on the outcome.

The investigators found data regarding muscle synthesis were scarce and inconclusive.

The investigators found subgroup analyses showed no beneficial effect of a specific timing of protein intake on lean body mass, handgrip strength and leg press strength.

The investigators concluded there is a positive impact of protein supplementation on lean body mass of healthy adults and older adults, independently of intake timing.

Original title:
The Role of Protein Intake and its Timing on Body Composition and Muscle Function in Healthy Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials by Wirth J, Hillesheim E and Brennan L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32232404

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The more lean body mass a person has, the higher their resting metabolic rate. Resting metabolic rate is the total number of calories burned when your body is completely at rest. Resting metabolic rate supports breathing, circulating blood, organ functions and basic neurological functions.

Objectives:
Which types of exercise training (whole body vibration training, aerobic training, strength training and combined training) increase lumbar spine and femoral neck bone mineral density (BMD) in older postmenopausal women (PMW)?

Study design:
This review article included 16 RCTs with 1,624 subjects.

Results and conclusions:
The investigators found no significant change in lumbar spine bone mineral density following exercise training [MD = 0.01 g/cm², 95% CI = -0.01 to 0.02].

The investigators found no significant change in femoral neck bone mineral density following exercise training [MD = 0.00 g/cm², 95% CI = -0.01 to 0.01].

The investigators found, however, subgroup analysis by type of exercise training revealed that lumbar spine bone mineral density [MD = 0.01, 95% CI = 0.00 to 0.02] raised significantly when whole-body vibration (WBV) was employed as intervention compared with RCTs that utilized aerobic [MD = -0.01, 95% CI = -0.02 to -0.01], resistance [MD = 0.01, 95% CI = -0.04 to 0.06] or combined training [MD = 0.03, 95% CI = -0.01 to 0.08].

The investigators found, on the other hand, lumbar spine bone mineral density [MD = - 0.01, 95% CI = -0.02 to -0.01] reduced significantly when aerobic exercise training was used as intervention compared with RCTs that utilized resistance training, combined training or whole-body vibration. 

The investigators concluded whole-body vibration is an effective method to improve lumbar spine bone mineral density in older postmenopausal women.

Original title:
The Impact of Different Modes of Exercise Training on Bone Mineral Density in Older Postmenopausal Women: A Systematic Review and Meta-analysis Research by Mohammad Rahimi GR, Smart NA, […], Mohammad Rahimi N.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32055889

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Objectives:
Although exercise can improve insulin sensitivity, no adequate synthesis exists of exercise intervention studies with regard to their effect on insulin sensitivity. Therefore, this review article (meta-analysis) has beeen conducted.

Does exercise improve insuline sensitivity?

Study design:
This review article included data found across 2509 subjects (115 samples, 78 reports).
The median of mean age was 43 years.
The median of mean preintervention fasting insulin was 8 mU/L.

Results and conclusions:
The investigators found the overall mean effect size for 2-group postintervention comparisons was 0.38 [95% CI = 0.25-0.51, I2 = 0%] and for 2-group pre-post comparisons was 0.43 [95% CI = 0.30-0.56, I2 = 52%].

The investigators found higher mean insulin sensitivity for treatment than control subjects.

The investigators found the postintervention mean of 0.38 was consistent with treatment subjects ending studies with a mean fasting insulin of 6.8 mU/L if control participants’ mean fasting insulin were 7.9 mU/L.
Exploratory moderator analyses did not document different insulin sensitivity effect sizes across intervention characteristics or sample attributes.

The investigators concluded exercise is a valuable primary care and community health strategy for healthy adults to improve insulin sensitivity and lower the risk for diabetes conferred by insulin resistance.

Original title:
Insulin Sensitivity Following Exercise Interventions: Systematic Review and Meta-Analysis of Outcomes Among Healthy Adults by Conn VS, Koopman RJ, […], Hafdahl AR.

Link:
http://journals.sagepub.com/doi/pdf/10.1177/2150131913520328

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