The effect of initial support on fitness center use in new fitness center members. A randomized controlled trial

•There is a lack of research onwhat fitness centers do to support new members.•The effect of initial support delivered via telephone and e-mail was investigated.•There was an effect on bookings with a fitness trainer first six months.•There was no effect on days with visits or membership duration during four years.•More visits the first six months were associated with longer membership duration. This provider and participant blinded parallel-group randomized controlled trial aimed to investigate if initial support given to new members via telephone and e-mail, compared to self-directed use, had an effect on booking with a fitness trainer, number of visits to the center, and membership duration. Participants included 356 new members, 174 randomized to the intervention group, and 182 to the control group. The intervention group received support to use the fitness center facilities through two phone calls and one e-mail over the first eight weeks of their membership. The control group got usual practice, which is self-directed use. Participants in the intervention group were more likely to book at least one session with a fitness trainer during the first six months (odds ratio 1.6, 95% confidence interval (CI) 1.0–2.5). However, the intervention did not influence the number of visits (mean difference after four years −11.7 days, 95% CI −34.8 to 11.3) or time to membership termination during the follow-up period (hazard ratio 1.1, 95% CI 0.8–1.3). In conclusion, initial support to use the fitness center facilities given to new fitness center members via telephone and e-mail increased the proportion of bookings with a fitness trainer during the first months of the membership, but it did not have an effect on the number of visits or membership termination during four years.