Work economy following strength training in elderly : alterations in muscle strength, muscle thickness and lean mass upon work economy in elderly men following 12 weeks of strength training

Abstract

AIM: To investigate if alterations in muscle strength, muscle mass and muscle thickness were followed by changes in work economy. METHODS: Fifty elderly men (60 – 81 years) followed a 12 week undulating periodized strength training program: Lean mass (Muscle mass; Dual-energy X-ray absorptiometry), muscle strength (1RM; one repetition maximum, in leg press and leg extension), and muscle thickness (ultrasound; vastus lateralis and rectus femoris) were measured before and after the intervention. Work economy, determined as body mass adjusted oxygen consumption, were assessed while walking on a treadmill at 5 km/h at three different inclinations: 0 %, 4 % and 8 %; 5 min at each work load. RESULTS: In addition to significant increases in muscle strength and muscle mass (p < 0.001), the participants significantly improved their work economy at the three different work-loads by, respectively, 4.0% (0.3, 7.4) (median and 95% confidence intervals (p = 0.01)), 2.8% (-1.4, 7.1 (p = 0.016)) and 2.5% (-0.2, 5.0 (p < 0.006)). No significant positive associations were found between changes in muscle strength, muscle mass or muscle thickness upon work economy. CONCLUSION: 12 weeks of strength training improved work economy during inclined walking in elderly men. However, the results suggest that other factors than changes in muscle strength, mass and thickness are the mechanisms behind the improved work economy.