L-Glutamine Supplementation Enhances Strength and Power of Knee Muscles and Improves Glycemia Control and Plasma Redox Balance in Exercising Elderly Women
What this study found
L-glutamine improved glycemic control, redox balance, and knee muscle strength and power, with the clearest benefit when paired with exercise. After supplementation, D-fructosamine fell by 28% in NPE + Gln and 16% in PE + Gln, insulin fell by 23% in NPE + Gln, and GSH increased 2.1-fold in NPE + Gln and 2.0-fold in PE + Gln. Knee extensor and flexor performance also improved, including intragroup gains of 20.6% and 47.6% in NPE + Gln and 16.1% and 21.4% in PE + Gln, respectively. The authors concluded that L-glutamine, especially combined with physical exercise, enhanced muscle function,…
- Study & population
- Randomized 4-arm human intervention study in elderly Brazilian women aged 60 to 80 years from São Paulo, comparing exercising and non-exercising participants assigned to L-glutamine or placebo.
- Intervention
- Participants in the active intervention arms received oral L-glutamine 10 g once daily for 30 days, taken at lunchtime and diluted in 250 mL water.
- Key limitation
- The active intervention arms were small, with only 11 and 12 participants, and the study lasted just 30 days.
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Open PDFOriginal abstract
We investigated the effects of oral L-glutamine (Gln) supplementation, associated or not with physical exercises, in control of glycemia, oxidative stress, and strength/power of knee muscles in elderly women. Physically active (n = 21) and sedentary (n = 23) elderly women aged 60 to 80 years were enrolled in the study. Plasma levels of D-fructosamine, insulin, reduced (GSH) and oxidized (GSSG) glutathione, iron, uric acid, and thiobarbituric acid-reactive substances (TBARs) (lipoperoxidation product), as well as knee extensor/flexor muscle torque peak and average power (isokinetic test), were assessed pre- and post-supplementation with Gln or placebo (30 days). Higher plasma D-fructosamine, insulin, and iron levels, and lower strength/power of knee muscles were found pre-supplementation in the NPE group than in the PE group. Post-supplementation, Gln subgroups showed higher levels of GSH, GSSG, and torque peak, besides lower D-fructosamine than pre-supplementation values. Higher muscle average power and plasma uric acid levels were reported in the PE + Gln group, whereas lower insulin levels were found in the NPE + Gln than pre-supplementation values. TBARs levels were diminished post-supplementation in all groups. Gln supplementation, mainly when associated with physical exercises, improves strength and power of knee muscles and glycemia control, besides boosting plasma antioxidant capacity of elderly women.