Long-Term Adaptations in the Squat, Bench Press, and Deadlift: Assessing Strength Gain in Powerlifting Athletes

Purpose: Understanding strength changes with resistance training is important in human performance. It also enables better understanding into the expected magnitude of strength increase and factors that influence this change over time. Methods: Squat, bench press, and deadlift scores were collated from 407 powerlifting meets (n = 1896 unique competitors: similar to 625 females, similar to 1270 males) between 2003 and 2018. Absolute (in kilograms) and relative starting strength (in kilograms per body weight) for each lift type was expressed for both sexes. Maximum and overall strength gain per day and per year (in kilograms) was calculated by comparing first and final, or maximum scores for each lift, respectively, and considered based on strength quartile classification. Paired and independent t-tests compared strength changes from baseline and between sexes. One-way ANOVAs compared strength changes between quartiles. Pearson correlations assessed relationships between strength changes over time, and baseline strength, number of competitions, and total days competing. Results: Maximum strength adaptations were greater for squat (20.2-25.4 kg.yr(-1)) and deadlift (18.1-21.1 kg.yr(-1)) compared with bench press (10.5-12.8 kg.yr(-1), P <= 0.001). However, the change in absolute (all lifts: P = 0.247-0.379) and relative strength (all lifts: P = 0.641-0.821) did not differ between sexes. For females, maximum strength gain per day did not differ by quartile (all lifts: P = 0.091-0.746), nor did overall strength gain per day (P = 0.151-0.575). Conversely, males in the fourth quartile generally displayed lower maximum and overall strength gain per day. Conclusions: These findings show differences in strength gain between upper- and lower-body lifts, but not sex differences in the change in strength. In line with previous research, the strongest males likely gain strength more slowly than weaker counterparts. Professionals should consider this information in the training, assessment, and long-term benchmarking of athletes whose sports require a focus on muscular strength.