Creatine supplementation in conjunction with heavy resistance training has been shown to increase muscle volume and enhance muscle strength in young healthy subjects. Because ageing is associated with muscle atrophy, we investigated the effect of creatine supplementation on biochemical and contractile properties of skeletal muscle during exercise training in older males.

A double blind, randomised, placebo-controlled study was performed during a 1 year period. The study protocol was approved by the local Ethics Committee. After signing an informed consent, twenty sedentary males (65 ± 1 years) agreed to participate in a supervised fitness training programme (2-3 sessions per week) which involved both endurance exercise (~30 min at 65-80 % of maximal heart rate reserve) and moderate-resistance training (six exercises, two series of 30 contractions at an intensity of 30RM). Subjects ingested creatine monohydrate (5 g day^-1; CR; n = 10) or placebo (P; n = 10; maltodextrine). At baseline and after 6 and 12 months, maximal isometric torque (T_max) of the knee-extensor muscles was evaluated on an isokinetic dynamometer, a maximal graded cycle ergometer test was performed, body composition was measured by hydrostatic weighing and a needle biopsy was taken from m. vastus lateralis (n = 7). Treatment effects were evaluated using two-way ANCOVA, and a one-way ANOVA was used to compare within groups. Data are given as means ± S.E.M.

Muscle total creatine content at baseline was similar in P (145 ± 5 mmol (kg dry wt)^-1) and CR (135 ± 10 mmol (kg dw)^-1). Compared with P, 6 months (P: 138 ± 7 mmol (kg dw)^-1; CR: 157 ± 8 mmol (kg dw)^-1) and 12 months (P: 137 ± 5 mmol (kg dw)^-1; CR: 164 ± 5 mmol (kg dw)^-1) of creatine supplementation did not significantly increase total creatine content. Furthermore, training or creatine supplementation did not significantly alter T_max in either group. Compared with baseline, V_O2,max increased (P < 0.05) from 2329 ± 134 to 2802 ± 178 ml min^-1 in P and from 2201 ± 80 to 2924 ± 261 ml min^-1 in CR after 6 and 12 months, respectively. Furthermore, by the end of the study, fat-free mass was significantly increased within CR (+1.2 ± 0.4 kg) but not within P (+0.2 ± 0.1 kg) and per cent body fat decreased (P < 0.05) by ~1.5 % within both groups.

It is concluded that in contrast to the prevailing data in younger subjects (20-25 years), oral creatine supplementation does not significantly increase muscle total creatine content and does not enhance the impact of exercise training on muscle functional capacity in males more than 60 years old.