Inter-Individual Different Responses to Continuous and Interval Training in Recreational Middle-Aged Women Runners.

A crucial subject in sports is identifying the inter-individual variation in response to training, which would allow creating individualized pre-training schedules, improving runner's performance. We aimed to analyze heterogeneity in individual responses to two half-marathon training programs differing in running volume and intensity in middle-aged recreational women. 20 women (40 ± 7 years, 61 ± 7 kg, 167 ± 6 cm, and VOmax = 48 ± 6 mL⋅kg⋅min) underwent either moderate-intensity continuous (MICT) or high-intensity interval (HIIT) 12-week training. They were evaluated and training with maximal incremental tests in the laboratory (VOmax) and in the field (time to exhaustion, TTE; short interval series and long run). All the women participated in the same half-marathon and their finishing times were compared with their previous times. Although the improvements in the mean finishing times were not significant, MICT elicited a greater reduction (3 min 50 s, = 0.298), with more women (70%) improving on their previous times, than HIIT (reduction of 2 min 34 s, = 0.197, 50% responders). Laboratory tests showed more differences in the HIIT group ( = 0.008), while both groups presented homogeneous significant ( < 0.05) increases in TTE. Both in the short interval series and in the long run, HIIT induced better individual improvements, with a greater percentage of responders compared to MICT (100% vs 50% in the short series and 78% vs 38% in the long run). In conclusion, variability in inter-individual responses was observed after both MICT and HIIT, with some participants showing improvements () while others did not () in different performance parameters, reinforcing the idea that individualized training prescription is needed to optimize performance.