October 2024

To Speed or Not to Speed – Lift, That is?

Read any layperson’s magazine or news article about resistance training (RT) and you’ll be cautioned frequently about doing the lifts slowly, with good form and proper breathing patterns. In other words, don’t fling the weights and don’t hold your breath.

All is good advice.

But recent years have brought in a new concept of RT: higher speed, or velocity-based (VB), lifting. This model is, on the surface, functionally valuable, especially for athletes but also for older adults. That is, faster lifts = more power = more functionality.

But does it really work? A team of researchers compared the effects of 2 VB programs where the total volumes were matched so that the only difference was the speed of the lifts. A within-person, between-leg research design was used on 10 resistance-trained adults. One leg was trained at low velocity (LV) while the other was trained at high velocity  (HV). The sets were limited by how much velocity was lost: for the LV, a 15% loss was the stopping point; for HV, it was 30% since muscles lose speed before they lose strength. Unilateral training was done 2/wk for 9 weeks. Subjects’ legs were tested for 1 repetition max (1RM), maximal voluntary contraction (MVC), rate of force development (RFD), average velocity (AV), power output (PO), muscle thickness (MT), pennation angle (PA), and fascicle length (FL) – all on the leg press device.

No differences were found between legs. Both programs increased 1RM, MVC, PO, and MT. Otherwise, no structural changes were noted despite substantial improvements in strength and power. So lift slow, lift fast, but mainly, just lift for life.                                                                

JSCR Mar. 2024

Hamstrings Get Their Just Rewards

Hamstrings are those big, usually-tight muscles in the back of the thigh. They’re the ones we often see sprinters grab as they pull up during a race, in obvious pain. They’re the ones that are implicated in the epidemic of female athletes’ anterior cruciate ligament tears. So finding the best ways to train them has been a goal of athletic trainers for years.

One measure of a muscle’s ability to resist disruption is having a low shear modulus (SM). According to Wikipedia, SM is the “elastic shear stiffness of a material and … defined as the ratio of shear stress to the shear strain.” In lay terms, a “small shear modulus value indicates a solid is soft or flexible. Little force is needed to deform it.” (https://www.thoughtco.com/shear-modulus-4176406) A muscle with a low SM is more supple, less stiff, and less likely to tear under normal circumstances.

A Japanese study had 3 groups of 12 doing 2- or 3-sessions/wk and a control group for 10 weeks. The training groups did stiff-leg (or Romanian (RDL)) dead lifts with 5 second sloooow negatives. SM, max isometric torque, and muscle volumes were assessed pre- and post-study.

One of the deeper muscles significantly reduced its SM whereas the other 3 biarticular muscles did not change. However, positive changes occurred in the isometric torque of the entire muscle group with notable increases in the semimembranosus (the deep muscle, above) volume. The study concluded that eccentric-only resistance training decreases passive stiffness when done 2-3 times a week….which is a good thing overall.           

MSSE July 2024

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