How often should you train with a personal trainer to see results

There is no magic number, but there is data

When people ask «how many times a week should I train?», they are looking for a precise number. Research offers something more useful: we know how strength and muscle mass change, on average, as frequency changes, and we also know how cautiously that data should be read. It is worth clarifying right away that «frequency» is used in different ways: how many training sessions you do in a week, or how many times in the week the same muscle group is trained. Many studies on muscle growth reason mainly in terms of this second definition.

The figures that follow come from meta-analyses, meaning studies that pool and compare many smaller pieces of research. They are averages across groups of people, mostly young, healthy adults, and should be read as indications of a trend, not as predictions for your own case. Where we cite an «effect size» (ES), this is a standardised measure of change, not kilograms or centimetres.

Frequency and strength: what the meta-analysis shows

A systematic review and meta-analysis from 2018 (Grgic and colleagues, Sports Medicine) pooled 22 studies comparing different weekly resistance training frequencies. According to PubMed, the effect of frequency on strength gains was significant (p = 0.003), with effect sizes rising as sessions increased: 0.74 for training once a week, 0.82 for twice, 0.93 for three times and 1.08 for four or more.

The finding needs careful reading, though. When the researchers considered only the studies in which total training volume was the same across groups, the effect of frequency was no longer significant (p = 0.421). The authors conclude that the advantage seems to depend mainly on the extra volume that a higher frequency allows you to accumulate, rather than on frequency itself. In addition, most of the studies were conducted on untrained people, and the advantages of higher frequencies were clearer in multi-joint upper-body exercises, in women, and in young adults as opposed to middle-aged and older adults.

A second meta-analysis (Ralston and colleagues, 2018, Sports Medicine - Open), covering 12 studies and 74 treatment groups, reached a consistent conclusion. With volume equated, the difference between low frequency (one day a week) and high frequency (three or more) was negligible (mean effect size 0.03, 95% confidence interval -0.20 to 0.27), while for upper-body strength high frequency was superior to low frequency (mean effect size 0.48; 95% confidence interval 0.20 to 0.76). The authors point out that the current data do not show a strong correlation between weekly frequency and maximal strength in a mixed population.

Frequency and muscle growth

As for muscle mass, a 2016 meta-analysis (Schoenfeld and colleagues, Sports Medicine) of 10 studies found that higher frequencies were associated with a greater effect size for hypertrophy than lower frequencies (0.49 versus 0.30; p = 0.002). Comparing studies in which muscle groups were trained one to three times a week on a volume-equated basis, the authors inferred that the major muscle groups should be trained at least twice a week to maximise growth, leaving open whether three times is better than two.

A broader review published at the end of 2018 (Schoenfeld, Grgic and Krieger, Journal of Sports Sciences) included 25 studies and reopened the picture: with volume equated, there was no significant difference between higher and lower frequencies, whether in direct measures of growth, in people who were already trained, or when upper and lower body were considered separately. In the analyses where volume was not equated, an advantage for higher frequencies appeared, but the difference between one and three or more days a week was modest. The authors speak of strong evidence that, for a given volume, the frequency per muscle group can be chosen according to personal preference. The two reviews are best read together: the second includes more studies (25 against 10), so it is more prudent to conclude that frequency matters less than total training volume.

The common thread is volume. A 2016 meta-analysis (Schoenfeld, Ogborn and Krieger, Journal of Sports Sciences), covering 15 studies and 34 treatment groups, estimated that each additional weekly set was associated with an increase in effect size of 0.023, corresponding to an increase in percentage gain of 0.37%; the difference between higher and lower volumes was 0.241 in effect size, equal to a 3.9% difference in gain. It is a graded, small-to-moderate relationship, valid on average and with all the usual caveats: more work makes you grow more, but within the limits of recovery and the time you have available.

What this means if you train with a personal trainer

In practical terms, the data do not suggest that two well-structured sessions a week are too few: in the strength meta-analysis, training twice a week has an effect size of 0.82, between that of once a week (0.74) and that of three times (0.93), and a programme in which each muscle group is trained twice a week is consistent with the indication that emerged for muscle growth. For someone starting from scratch, two sessions followed regularly are therefore a reasonable starting point, and for someone who already trains consistently a single guided session can be combined with well-planned independent work. It is not a universal rule: these are working hypotheses to be checked on you, session after session.

The second point is sustainability. Since, with volume equated, frequency seems to matter less than the total work you manage to do, it makes more sense to start from a frequency you can genuinely keep than from the ideal one on paper: a plan can always grow, starting over is harder. Then there is progression: repeating the same workout for months leads to a plateau even with plenty of sessions, because what matters is that each session asks slightly more than the last (loads, repetitions, exercises). Recovery is part of the programme too: sleep, work commitments and busy periods of daily life affect how you respond to training, and a guided programme adapts the week instead of forcing it. That is why, for us, frequency is not a number decided in advance: we start from how many sessions you can sustain consistently and build progression session after session.

Limits of the studies and a note of caution

The meta-analyses cited have limits that should be stated. Much of the evidence includes untrained people and relatively short durations; the populations are heterogeneous (age, sex, experience), exercises and measurement methods vary from study to study, and effect sizes do not translate directly into extra kilograms or centimetres. The authors themselves point to the need for more data on people who are already trained. Averages also conceal considerable individual differences: on the same programme, two people can respond differently.

Finally, a health note: if you have cardiovascular or musculoskeletal conditions, persistent pain, an ongoing pregnancy, take medication, or have not trained for a long time, talk to your doctor before increasing how often you train. This article is for information only; it is not a substitute for medical advice and does not guarantee specific results.