The anabolic supplement HMB has an effect even if only a single dose is taken before a strength training session, but the effect is small. Like creatine, HMB apparently only works really well after a loading period, nutritionists at Florida State University conclude. The researchers did an experiment with 22 male students who had never done weight training before. The men trained their leg muscles on a leg extension machine in a way that caused severe muscle damage and soreness.
On one occasion the subjects were given a placebo before and after the workout; on another occasion they took 3 g HMB 60 minutes before training their legs [HMB-Pre], and on yet another occasion they took 3 g HMB just after finishing a session [HMB-Post]. The blood HMB level peaks about sixty minutes after intake.
Taking HMB before the workout had a positive effect the researchers discovered. In the days after the workout the HMB-Pre subjects reported less muscle soreness than the other subjects, as the figure below shows.
The HMB had less effect on objective muscle damage markers. There was no clear effect on the concentration of creatine kinase [CK], but there was an effect on the concentration of lactate dehydrogenase [LDH]. The LDH concentration didn’t rise after the subjects had taken HMB an hour before their workout; on the other occasions it did rise.
CK and LDH are enzymes that are active in muscle cells. If the muscle cells are damaged then the enzymes leak into the blood. The more CK and LDH you find in the blood, the greater the muscle damage.
The one-time doses of HMB – pre and post – had no effect on strength recovery in the days after the heavy workout.
“It appears that HMB may need a loading period prior to exercise in order to significantly attenuate the rise in indices of muscle damage relative to placebo and HMB-Post conditions”, the researchers write. “Similar to creatine based studies, we suggest that future researchers examine how loading effects the concentration of HMB into skeletal muscle tissue, and what variables including duration of the loading period, and dosage loaded play in saturating skeletal muscle.”