The purpose of this study was to compare the number of testing sessions required to achieve consistent 1 repetition maximum (1RM) strength measurements in untrained old and young women. Consistency of measurement was defined as consecutive 1 RM strength measures that increased by 1 kg or less. Untrained old (n = 6, age 66 +/- 5 years) and untrained young (n = 7, age 23 +/- 4 years) women were repeatedly strength-tested for bilateral concentric knee extension 1 RM strength until consecutive measurements were increased by no more than 1 kg. At least 48 hours of rest was allowed between 1 RM measurements. The old subjects required significantly more testing sessions (8-9 sessions) compared with the young subjects (3-4 sessions) to achieve the same absolute consistency of measurement (p < 0.05). Absolute increase in strength between the first and final testing sessions did not differ between groups (young = 11 +/- 4 kg and old = 13 +/- 2 kg) (p > 0.05). The relative increase was significantly greater in the older subjects (young = 12 +/- 5%; old = 22 +/- 4%) (p < 0.05). In conclusion, older subjects require more practice and familiarization and show greater relative increases in 1RM strength when compared with younger subjects of the same experience level. This is important to consider, especially when evaluating the magnitude of strength increase in response to resistance training.