Older lifters gain strength and a growth factor boost, women especially

Muscle strength declines with age, and resistance training is the standard countermeasure. Behind the strength story sits a hormonal one: IGF-1, a growth factor involved in tissue growth and repair, and its main binding protein, IGFBP-3. Whether lifting actually raises circulating IGF-1 in older people has been genuinely contested, with individual trials reporting contradictory results. This review pooled the randomised evidence to settle what resistance training does to strength, IGF-1 and IGFBP-3 in healthy elderly people.

The authors systematically searched PubMed, CINAHL, Medline, Google Scholar and Scopus up to May 2020 for randomised controlled trials comparing older adults who performed resistance training with control individuals who did not. Eleven eligible trials were identified and analysed following standard review guidelines. They pooled changes in serum IGF-1 and IGFBP-3 alongside muscle strength measured in the leg press and bench press, and ran subgroup analyses by sex and by whether training lasted more or less than 12 weeks.

Resistance training was associated with a significant rise in serum IGF-1 of 17.34 ng/ml, together with clear strength gains in both the leg press and the bench press. IGFBP-3, by contrast, did not change significantly. The subgroup analyses added texture: the IGF-1 elevation was significant only in women, and it appeared after training programmes both longer and shorter than 12 weeks, at 21.98 and 15.31 ng/ml respectively. The strength benefits were consistent throughout.

This pooling resolves some of the contradiction in earlier findings by suggesting the average effect of resistance training on IGF-1 in older adults is a modest rise rather than nothing. The sex split is the most intriguing wrinkle, since women drove the hormonal response and the review cannot explain why. The authors themselves call for further work on the mechanisms linking training, IGF-1, IGFBP-3 and strength. What is not in dispute is the strength outcome, which aligns with a large existing literature on lifting in later life.

For an older person weighing up resistance training, the strength result is the dependable part: pooled trials show meaningful gains against doing nothing. The hormonal finding is interesting rather than actionable, a hint that lifting nudges a growth and repair signal upward, particularly in women. Since the health significance of a modest IGF-1 rise is not established here, it is best read as background biology rather than a target. The case for training in later life rests comfortably on the strength gains alone.