Does Strength Training in Machines Improve Strength and Power in Functional Tasks Among Elderly?

Abstract

PURPOSE: To determine whether high power machine strength training improves strength and power in functional strength tasks among elderly subjects >65 years. METHODS: 33 healthy, high functioning elderly subjects (18 male, 15 female) were randomized to a high power machine strength training group (HPMSG, n=23, 69+4 yr) or a non-training control group (CON, n=1 0, 69+4 yr). HPMSG and CON performed the following tests: Functional strength tests; 30s Chair stand, Modified PILE-test (Progressive Isoinertial Lifting Evaluation), Stair Sprint test. Traditional strength tests; 45 degree Leg press machine and Bench press in Smith machine (TechnoGym™). Force and power data were collected using force platform (Chair stand), linear encoder (PILE lift and leg press), and photocell based timing equipment (stair sprint). HPMSG trained 2x.wk-1, 3 sets (60, 80, 80% of weekly adjusted 1RM) x 8 reps for 11 weeks in 5 machine based exercises (leg press, seated row, lat pulldown, shoulder press, bench press). Subjects were instructed to perform each repetition at maximal effort. RESULTS: HPMSG improved bilateral leg press max force (Mean+SE) 20+5% (CON 4+3%, p=0.04), 30- sec Chair Sit-to-Stand power 14.5+5% (CON -4.1+5%, p=0.06) and Modified PILE lifting power 19.2+4% (CON 3.3+5%, p=0.01). However average power output during a 6-step stair sprinting task with 0, 10, or 20 kg external loads was not significantly improved after high power strength training (8.4 + 2 vs. 6.4+2%, p=0.64). CONCLUSIONS: These data suggest that supervised “high power” machine strength training at 80% 1RM with maximal intended velocity significantly improves functional strength and power in bilateral activities such as rapid chair standing and box lifting from the floor. However, power gains were not transferred to the unilateral task of rapid stair climbing.