Restricting lumbar spine flexion redistributes and changes total mechanical energy expenditure during lifting.

Minimizing lumbar spine flexion during lifting requires greater lower extremity joint motion. However, the effects of these kinematic changes on lumbar and lower extremity joint kinetics are unknown. Further, it is unclear whether the distribution of biomechanical demands throughout the lumbar spine and lower extremity during lumbar spine flexion restricted lifting are modulated by task factors like lift origin height and object mass.

The addition of blood flow restriction during resistance exercise does not increase prolonged low-frequency force depression.

At a given exercise intensity, blood flow restriction (BFR) reduces the volume of exercise required to impair post-exercise neuromuscular function. Compared to traditional exercise, the time course of recovery is less clear. After strenuous exercise, force output assessed with electrical muscle stimulation is impaired to a greater extent at low versus high stimulation frequencies, a condition known as prolonged low-frequency force depression (PLFFD).

Can we enable individuals to reach further down without rounding their backs before beginning a lift? Examining the influence of starting foot and trunk position on reach depth.

There is disagreement regarding the efficacy of 'safe' lifting recommendations for reducing low back disorder risk. These recommendations commonly focus on minimising lumbar spine flexion, which limits the range of allowable starting lift positions for that person. This study evaluated whether starting postural adaptations could allow a person to reach down further without rounding their lumbar spine before beginning a lift.

A comparison of five methods to normalize joint moments during running.

Background: Net joint moments (NJM) are typically normalized for a (combination of) physical body characteristics such as mass, height, and limb length using ratio scaling to account for differences in body characteristics between individuals. Four assumptions must be met when normalizing NJM data this way to ensure valid conclusions. First, the relationship between the non-normalized NJM and participant characteristic should be linear.

Comparison of 5 Normalization Methods for Knee Joint Moments in the Single-Leg Squat.

Ratio scaling is the most common magnitude normalization approach for net joint moment (NJM) data. Generally, researchers compute a ratio between NJM and (some combination of) physical body characteristics (eg, mass, height, limb length, etc). However, 3 assumptions must be verified when normalizing NJM data this way.

Mechanical Energy Expenditure at Lumbar Spine and Lower Extremity Joints During the Single-Leg Squat Is Affected by the Nonstance Foot Position.

Hirsch, SM, Chapman, CJ, Frost, DM, and Beach, TAC. Mechanical energy expenditure at lumbar spine and lower extremity joints during the single-leg squat is affected by the nonstance foot position. J Strength Cond Res 36(9): 2417-2426, 2022-Previous research has shown that discrete kinematic and kinetic quantities during bodyweight single-leg squat (SLS) movements are affected by elevated foot positioning and sex of the performer, but generalizations are limited by the high-dimensional data structure reported.

Considerations for Velocity-Based Training: The Instruction to Move "As Fast As Possible" Is Less Effective Than a Target Velocity.

Hirsch, SM and Frost, DM. Considerations for velocity-based training: the instruction to move "as fast as possible" is less effective than a target velocity. J Strength Cond Res 35(2S): S89-S94, 2021-In addition to the potential benefits with monitoring training intensity with velocity-measuring tools during exercise, these devices also provide an opportunity for researchers and practitioners to provide feedback and instruction to performers in a new way.