PURPOSE This study aimed to compare the effects of free-weight and machine-based resistance training on strength, hypertrophy, and joint discomfort. METHODS Thirty-eight resistance-trained men participated in an 8-wk resistance program allocated into free-weight ( n = 19) or machine-based ( n = 19) groups. Training variables were identical for both modalities, so they only differed in the use of barbells or machines to execute the full squat, bench press, prone bench pull, and shoulder press exercises. The velocity-based method was implemented to accurately adjust the intensity throughout the program. Strength changes were evaluated using eight velocity-monitored loading tests (four exercises × two modalities) and included the relative one-repetition maximum (1RM Rel ), as well as the mean propulsive velocity against low (MPV Low ) and high (MPV High ) loads. Ultrasound-derived cross-sectional area of quadriceps (proximal and distal regions), pectoralis major, and rectus abdominis was measured to examine hypertrophy. Complementarily, Western Ontario and McMaster Universities and Disabilities of the Arm, Shoulder and Hand questionnaires were administrated to assess changes in lower- and upper-limb joint discomfort. Outcomes were compared using ANCOVA and percentage of change (∆) statistics. RESULTS Each group significantly ( P < 0.001) increased 1RM Rel , MPV Low , and MPV High for both modalities tested, but especially in the one they trained. When considering together the eight exercises tested, strength changes for both modalities were similar (∆ differences ≤1.8%, P ≥ 0.216). Likewise, the cross-sectional area of all the muscles evaluated was significantly increased by both modalities, with no significant differences between them (∆ difference ≤2.0%, P ≥ 0.208). No between-group differences ( P ≥ 0.144) were found for changes in stiffness, pain, and functional disability levels, which were reduced by both modalities. CONCLUSIONS Free-weight and machine-based modalities are similarly effective to promote strength and hypertrophy without increasing joint discomfort.

中文翻译：

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自由重量训练和机器训练对于力量和增肌同样有效：挑战传统神话。

目的本研究旨在比较自由重量和机器阻力训练对力量、肥大和关节不适的影响。方法 38 名接受过阻力训练的男性参加了为期 8 周的阻力计划，并被分为自由重量组 (n = 19) 或器械组 (n = 19)。两种模式的训练变量是相同的，因此它们仅在使用杠铃或机器来执行全蹲、卧推、俯卧卧推和肩部推举练习方面有所不同。采用基于速度的方法来准确调整整个计划的强度。使用八次速度监测负载测试（四次练习 × 两种模式）评估力量变化，包括相对单次重复最大值 (1RM Rel )，以及低 (MPV Low ) 和高 (MPV High ) 的平均推进速度负载。测量超声衍生的股四头肌（近端和远端区域）、胸大肌和腹直肌的横截面积以检查肥厚情况。作为补充，西安大略大学和麦克马斯特大学进行了手臂、肩部和手部残疾调查问卷，以评估下肢和上肢关节不适的变化。使用 ANCOVA 和变化百分比 (Δ) 统计数据对结果进行比较。结果 对于两种测试模式，每组的 1RM Rel、MPV Low 和 MPV High 均显着增加 (P < 0.001)，但在他们训练的模式中尤其如此。当一起考虑测试的八个练习时，两种模式的力量变化相似（Δ差异≤1.8％，P≥0.216）。同样，两种方式评估的所有肌肉的横截面积均显着增加，但它们之间没有显着差异（Δ差异≤2.0％，P≥0.208）。僵硬、疼痛和功能障碍水平的变化没有发现组间差异（P≥0.144），两种治疗方式均降低了这些变化。结论 自由重量和机器训练对于促进力量和肥大同样有效，且不会增加关节不适。