Feasibility of Velocity Loss-Based Volume Prescription During Constant-Load and Chain-Based Smith Machine Back Squats
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 26
- 试验地点
- 1
- 主要终点
- The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds
研究概览
简要总结
The goal of this observational study was to evaluate the feasibility of percentage of velocity loss (%VL)-based approaches for prescribing training volume during constant-load and chain-based Smith machine back squats. The study aimed to answer whether %VL can be expressed as the maximum number of repetitions (%Rep) in constant-load and chain-based Smith machine squats. Twenty-six resistance-trained men performed repetitions-to-failure tests under variable (VRT) and constant resistance training (CRT). The %Rep attained before reaching different levels of effort were compared between VRT and CRT across various loads and sessions. Furthermore, this study evaluated the influence of different factors on the predictive accuracy of the %Rep-%VL relationships. These findings will provide evidence-based evidence in prescribing and monitoring intra-set volume.
详细描述
The goal of this observational study was to evaluate the feasibility of percentage of velocity loss (%VL)-based approaches for prescribing training volume during constant-load and chain-based Smith machine back squats. The study aimed to answer whether %VL can be expressed as the maximum number of repetitions (%Rep) in constant-load and chain-based Smith machine squats. Twenty-six resistance-trained men performed repetitions-to-failure tests at 85%, 75%, and 65% of their constant-load one-repetition maximum (1RM) under variable (VRT; 40% of the total external load provided by chains) and constant resistance training (CRT; 0% chains). The %Rep attained before reaching low (10% VL), moderate (20% VL), and high (30% VL) levels of effort were compared between VRT and CRT across various loads and sessions. Furthermore, this study evaluated the influence of regression type (individual vs. general), load specificity (load-specific vs. multiple-load), and loading configuration (CRT vs. VRT) on the predictive accuracy of the %Rep-%VL relationships established in session 1 for estimating %Rep in session 2. These findings will provide evidence-based evidence in prescribing and monitoring intra-set volume.
研究设计
- 研究类型
- Observational
- 观察模型
- Case Crossover
- 时间视角
- Cross Sectional
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- Male
- 接受健康志愿者
- 是
入选标准
- •at least 1 year of resistance training experience, performing back squats at least once per week.
- •proficiency in the Smith machine back squat executed at maximal intended velocity.
- •a constant-load 1RM of ≥ 1.5 times their body mass.
- •no reported musculoskeletal injuries in the past three months.
排除标准
- •Voluntary withdrawal or injury.
- •Not satisfied with inclusion label.
结局指标
主要结局
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds
时间窗: April 1st, 2026
The %Rep attained before reaching the 10%, 20%, and 30% VL thresholds was recorded across all loads, sessions, and loading configurations.
The %rep predictive accuracy
时间窗: April 1st, 2026
To assess predictive accuracy, second-order polynomial regression equations were generated from the first session of each loading configuration using all repetitions within a set, setting %Rep as the dependent variable and %VL as the independent variable. These equations were constructed using different regression types (individual vs. general), load specificities (load-specific vs. multiple-load), and loading configurations (CRT vs. VRT). During the second session, the actual %VL recorded after reaching the 10%, 20%, and 30% VL thresholds was substituted into the corresponding first-session equations to derive the predicted %Rep. Then, the absolute estimation error was calculated as (\|actual %Rep - predicted %Rep\|). In cases where muscular failure occurred before a specific %VL threshold was reached (e.g., 30% VL), the %VL of the final completed repetition was recorded, and the corresponding actual %Rep was defined as 100%.
次要结局
未报告次要终点
研究者
Zongwei Chen
Principal Investigator
South China Normal University