Grip Strength Lab

ILLINOIS STATE UNIVERSITY

SCHOOL OF KINESIOLOGY AND RECREATION

KNR 342, Occupational Biomechanics

Grip Strength Lab

OBJECTIVES:

1. To demonstrate the changing grip strength in relation to differences in spread of the grip dynamometer

READINGS: From Chaffin & Andersson , Muscle mechanics section 2.3.5

The length-tension relationship describes the change in the force producing capability of muscle related to differences in length at the time of activation. For isometric actions, the difference in force is mainly attributed to differences in overlap of the actin and myosin myofilaments. Difference may also be attributed to variation in the contribution of the elastic component of muscle, but the affect during isometric activity is not as great as during dynamic activity.

The purpose of this lab is to demonstrate some in-vivo applications of the relationship. Because the actual length of muscle cannot be directly measured in-vivo, and because the measured output is an externally applied force and not muscle tension, the relationship to be demonstrated is better referred to as the joint position-grip strength relationship.

In the lab, data will be collected under three scenarios to demonstrate how the measured grip strength varies according to the joint position at the time of measurement:

1) Grip width varied. Typically, the grip dynamometer is aligned so that the pressure bar is aligned with the metacarpal heads (knuckles). In this lab, the pressure bar will be aligned with 3 different positions: 1) at the distal phalangeal joint of the middle finger; 2) with the metacarpal head of the middle finger; 3) with the center of the palm. Keep your elbow straight and wrist in the neutral position. Note: for each position, record the distance between the grip handle and finger grip.

2) Elbow position varied. Some of the muscles responsible for flexion of the fingers originate on the medical epicondyle of the humerus. Thus, position of the elbow...