EFFECTS OF RESISTANCE TRAINING ON STRENGTH, POWER, AND SELECTED FUNCTIONAL ABILITIES OF WOMEN AGED 75 AND OLDER

OBJECTIVE: To determine the effects of 12 weeks of progressive resista nce strength training on the isometric strength, explosive power, and selected functional abilities of healthy women aged 75 and over. DESIG N: Subjects were matched for age and habitual physical activity and th en randomly assigned into either a control or an exercise group. SETTI NG: The Muscle Function Laboratory, Royal Free Hospital School of Medi cine, London. PARTICIPANTS: Fifty-two healthy women were recruited thr ough local and national newspapers. Five dropped out before and seven (4 exercisers and 3 controls) during the study. Pre- and posttraining measurements were obtained from 20 exercisers (median age 79.5, range 76 to 93 years) and 20 controls (median age 79.5, range 75 to 90 years ). INTERVENTIONS: Training comprised one supervised session (1 hour) a t the Medical School and two unsupervised home sessions (supported by an exercise tape and booklet) per week for 12 weeks. The training stim ulus was three sets of four to eight repetitions of each exercise, usi ng rice bags (1-1.5 kg) or elastic tubing for resistance. The exercise s were intended specifically to strengthen the muscles considered rele vant for the functional tasks, but were not to mimic the functional me asurements. No intervention was prescribed for the controls. MEASUREME NTS: Pre- and posttraining measurements were made for isometric knee e xtensor strength (IKES), isometric elbow flexor strength (IEFS), handg rip strength (HGS), leg extensor power (LEP), and anthropometric indic es (Body impedance analysis, arm muscle circumference, and body weight ). Functional ability tests were chair rise, kneel rise, rise from lyi ng on the floor, 118-m self-paced corridor walk, stair climbing, funct ional reach, stepping up, stepping down, and lifting weights onto a sh elf. Pre- and posttraining comparisons were made using analysis of var iance or analysis of covariance (using weight as a covariate) for norm ally distributed continuous data and one-sided Fishers exact test (2x2 table) for discontinuous data. RESULTS: Improvements in IKES (mean ch ange 27%, P = .03), IEFS (22%, P = .05), HGS (4%, P = .05), LEP/kg (18 %, P = .05) were associated with training, but the improvement in LEP (18%, P = .11) did not reach statistical significance. There was an as sociation between training and a reduction in normal pace kneel rise t ime (median change 21%, P = .02) and a small improvement in step up he ight (median 5%, P = .005). The other functional tests did not improve . CONCLUSIONS: Progressive resistance exercise can produce substantial increases in muscle strength and in power standardized for body weigh t in healthy, very old women. However, isolated increases in strength and LEP/kg may confer only limited functional benefit in healthy, inde pendent, very old women.