Effect of Squat Depth and Barbell Load on Relative Muscular Effort in Squatting

Abstract

Resistance training is used to develop muscular strength and hypertrophy. Large muscle forces, in relation to the muscle's maximum force-generating ability, are required to elicit these adaptations. Previous biomechanical analyses of multi-joint resistance exercises provide estimates of muscle force but not relative muscular effort (RME). The purpose of this investigation was to determine the RME during the squat exercise. Specifically, the effects of barbell load and squat depth on hip extensor, knee extensor, and ankle plantar flexor RME were examined. Ten strength-trained women performed squats (50-90% 1 repetition maximum) in a motion analysis laboratory to determine hip extensor, knee extensor, and ankle plantar flexor net joint moment (NJM). Maximum isometric strength in relation to joint angle for these muscle groups was also determined. Relative muscular effect was determined as the ratio of NJM to maximum voluntary torque matched for joint angle. Barbell load and squat depth had significant interaction effects on hip extensor, knee extensor, and ankle plantar flexor RME (p < 0.05). Knee extensor RME increased with greater squat depth but not barbell load, whereas the opposite was found for the ankle plantar flexors. Both greater squat depth and barbell load increased hip extensor RME. These data suggest that training for the knee extensors can be performed with low relative intensities but require a deep squat depth. Heavier barbell loads are required to train the hip extensors and ankle plantar flexors. In designing resistance training programs with multi-joint exercises, how external factors influence RME of different muscle groups should be considered to meet training objectives.

Effects of barbell back squat stance width on sagittal and frontal hip and knee kinetics

“…It is important to consider the stimulus of adjacent joints; therefore, we plotted ankle dorsiflexion kinematics and kinetics in Figures and , and descriptive statistics are provided as additional information for the ankle, in addition to L5/S1 NJM. In a NARROW squat, plantar flexor relative muscular effort is high and peaks toward the end of the ascent . These kinetic changes correspond with COP movement shifting toward the forefoot, albeit more so in NARROW (Figure ).…”

“…In a NARROW squat, plantar flexor relative muscular effort is high and peaks toward the end of the ascent. 27 These kinetic changes correspond with COP movement shifting toward the forefoot, albeit more so in NARROW ( Figure 3). Swinton et al 6 results demonstrated that a narrower squat position produced significantly higher ankle NJM than wider position, while our results did not significantly differ but demonstrated small to moderate effects in favor of the NARROW position (additional information, Table 2).…”

“…Based on anecdotal evidence, squatting in substantially wider position (ie, at or above ~1.5× greater trochanter width) can hinder depth and knee flexion. Greater knee flexion angles have been suggested to be a larger determinant of quadriceps utilization than external load when observing angle‐specific relative muscular efforts in the squat . This implies that a narrower squatting width (ie, between hip and shoulder width) under maximal range of motion conditions should, in general, stimulate the quadriceps more than a substantially wider position.…”

Kinematic and Electromyographic Activity Changes during Back Squat with Submaximal and Maximal Loading

“…Surface EMG has been widely used for assessment of muscle activities during squat, and it has been shown that the EMG activities of the muscles increased by increasing the loads during squatting in different studies [20–23]. Bryanton et al [24] studied the biomechanical analysis and relative muscular effort during squat while increasing the barbell load from 50% to 90% of 1RM but did not use EMG to determine the muscle activities and more importantly the maximal loading that we expect to see the kinetic and muscular activity changes. Therefore, we aimed to see the kinematic and muscular activity changes while we increase the loads from 80% to 90% and finally 100% of 1RM squatting.…”

Kinetic and Kinematic Changes during a 30-Repetition Bout of the Barbell Clean

“…Generally when the clean is performed and the athlete propels the barbell upward, they flex at the lower body joints to lower the Centre of Mass (COM) so that the barbell can be caught on the shoulders at a reduced height. As repetitions increased and the athletes became more fatigued, it is possible that they adopted the strategy to lower the COM through less hip flexion and more ankle dorsiflexion to reduce energy demand required to rise from a squat with the hips in a more extended position [23]. This altered lifting strategy is likely to reduce the effectiveness of the exercise.…”