Muscular Power during a Lifting Task Increases after Three Months of Resistance Training in Overweight and Obese Individuals

Strength and Power-Related Measures in Assessing Core Muscle Performance in Sport and Rehabilitation

While force-velocity-power characteristics of resistance exercises, such as bench presses and squats, have been well documented, little attention has been paid to load, force, and power-velocity relationships in exercises engaging core muscles. Given that power produced during lifting tasks or trunk rotations plays an important role in most sport-specific and daily life activities, its measurement should represent an important part of the test battery in both athletes and the general population. The aim of this scoping review was 1) to map the literature related to testing methods assessing core muscle strength and stability in sport and rehabilitation, chiefly studies with particular focus on force-velocity-power characteristics of exercises involving the use of core muscles, 2) and to identify gaps in existing studies and suggest further research in this field. The literature search was conducted on Cochrane Library databases, Scopus, Web of Science, PubMed and MEDLINE, which was completed by SpringerLink, Google Scholar and Elsevier. The inclusion criteria were met in 37 articles. Results revealed that among a variety of studies investigating the core stability and core strength in sport and rehabilitation, only few of them analyzed force-velocity-power characteristics of exercises involving the use of core muscles. Most of them evaluated maximal isometric strength of the core and its endurance. However, there are some studies that assessed muscle power during lifting tasks at different loads performed either with free weights or using the Smith machine. Similarly, power and velocity were assessed during trunk rotations performed with different weights when standing or sitting. Nevertheless, there is still scant research investigating the power-velocity and force-velocity relationship during exercises engaging core muscles in able-bodied and para athletes with different demands on stability and strength of the core. Therefore, more research is needed to address this gap in the literature and aim research at assessing strength and power-related measures within cross-sectional and intervention studies. A better understanding of the power-force-velocity profiles during exercises with high demands on the core musculature has implications for designing sport training and rehabilitation programs for enhancement of athletes' performance and/or decrease their risk of back pain.

Analysis of the Load-Velocity Relationship in Deadlift Exercise

The aim of this study was to analyze the relationship between movement velocity and relative load (%1RM) in the deadlift exercise. Fifty men (age = 23.8 ± 3.6 years, body mass = 78.2 ± 8.3 kg, height = 1.78 ± 0.06 m) performed a first evaluation (T1) consisting of a one-repetition maximum (1RM) test. Forty-two subjects performed a second evaluation (T2) after 6 weeks. Mean (MV), mean propulsive (MPV) and peak (PV) velocity measures of the concentric phase were analyzed. Load-velocity relationships were studied by fitting first order equations to the data using loads from 30-100% of 1RM. A comprehensive set of statistics for assessing bias and level of agreement to estimate the 1RM value from the different models was used. Stability of these relationships was assessed using the coefficient of variation (CV) and the intraclass correlation coefficient (ICC). General load-velocity equations provided good adjustments (R² ~; 0.91-0.93), however individual load-velocity regressions provided better adjustments (R² ~; 0.97). Individual estimations also showed higher agreement and more regular variation than general equations. Moreover, MPV showed smaller bias than the other velocity parameters (MV and PV). The stability analysis of the load-velocity relationships resulted in ICC values higher than 0.82 and CV lower than 3.0%. Monitoring repetition velocity allows estimation of the %1RM in the deadlift exercise. More accurate predictions of relative load can be obtained when using individualized regression equations instead of general equations.

Peak Rate of Force Development and Isometric Maximum Strength of Back Muscles Are Associated With Power Performance During Load-Lifting Tasks

This study investigates the relationship between peak force and rate of force development (RFD) obtained from maximal voluntary isometric contraction (MVC) of the back muscles and the power produced during a loaded lifting task. A group of 27 resistance-trained and 41 recreationally physically active men performed a maximal isometric strength test of the back muscles and a deadlift to high pull while lifting progressively increasing weights. Peak RFD correlated significantly with the peak and mean power produced during a deadlift to high pull with lower weights (from 20 to 40 kg), with r values ranging from .941 to .673 and from .922 to .633. The r² values ranged from .89 to .45 and from .85 to .40, explaining 89%–45% and 85%–40% of total variance. There were also significant relationships between MVC peak force and peak and mean values of power produced during a deadlift to high pull with weights ≥60 kg (r in range from .764 to .888 and from .735 to .896). Based on r², a moderate-to-high proportion of variance was explained (58%–79% and 54%–80%). These findings indicate that peak RFD obtained from MVC of the back muscles may be predictive of power performance during a lifting task at light loads. In addition to MVC peak force produced by back muscles, the ability of subjects to develop a high force in a short time should be evaluated in order to gain deeper insight into a loaded lifting performance, namely, in those prone to low back pain.