Nutrition & Food Sciences

Biography

Biography: Mylene aubertin-leheudre

Abstract

Aging is associated with losses of muscle mass, strength and quality which are strong risk factors of functional incapacities. Physical activity and nutrition are two of the most promising non-pharmacological avenues to counteract functional incapacities. More precisely, High Intensity Interval Training (HIIT), a short but intense physical activity training, is recognised to improve metabolic function, aerobic capacity and body composition in older adults. Another potential avenue is L-citrulline (CIT), a non-proteogenic-amino acid which seems to prevent the loss of muscle mass and strength in older adults. Preliminary results showed a beneficial additive effect of CIT and HIIT on muscle function in obese older adults. However, it has been shown that the amount of protein intake could influence physical adaptations following exercise intervention and affect also the efficacy of CIT to improve body composition in malnourished people. We aimed to evaluate if the initial amount of protein intake could influence the combined effect of CIT to HIIT on body composition, muscle strength and functional capacities in older adults. Thirty-eight sedentary obese (criteria: % fat mass (FM)) subjects (67±5yrs) who ingested CIT (10g/d; blind-condition) and completed a 12-week elliptical HIIT program (cycle:30sec>85% and 90sec at 65% of maximal predicted heart rate; 3x30min/week) were divided a-posteriori into 2 groups according to the initial amount of protein intake (PROT-: <1g.kg^-1.d^-1 (n=18) vs. PROT+: >1g.kg^-1.d^-1 (n=20)). Functional capacities (4m-walking test, chair and step tests), physical endurance (6MWT), muscle strengths (knee extensor strength (KES), handgrip (HS)), muscle power (Leg power rig; MP), body composition (DXA) were measured pre- and post-intervention.  No difference at baseline between groups except by design for protein intake ((PROT: 0.78g.kg^-1.d^-1 vs. PROT+: 1.33 g.kg^-1.d^-1). Following the intervention (CIT+HIIT), all subjects improved significantly (p<0.05) on waist circumference (103.2 vs. 100.4cm), total FM (37 vs. 35.9%) and fat-free-mass (FFM:46.5 vs. 47kg), KES (315 vs. 367N), HS (32.5 vs 34.3kg), MP (151 vs. 180W), 4-m walking test (0.74 vs. 0.68sec), step test (30 vs. 34rep), chair test (19.0 vs.15.8sec) and 6MWT (549 vs. 618m).  Regarding the initial protein intake effect, PROT- decreased significantly more gynoïd (PROT-: T0:41.4-T12:39.1% vs. PROT+: T0:38.7-T12:39.1%) and leg (PROT-: T0:37.3-T12:35.2% vs. PROT+:T0:34.9-T12:34.7%) FMs and improved significantly more leg FFM (PROT-: T0:16.3-T12:16.8kg vs. PROT+: T0:16.8-T12:16.7kg)and HS (PROT-: T0:32.7-T12:35.9kg vs. PROT+: T0:32.4-T12:32.8kg) than PROT+. Our results show that CIT+HIIT combination is more beneficial in obese older adults eating initially less than 1 g.kg^-1.d^-1 of proteins since they had greater improvements on body composition and muscle strengths. Further randomized controlled trial are needed to confirm these promising results since protein intake was studied a-posteriori.