Archie Young

Size and strength of the quadriceps muscles of old and young women

Abstract. Muscle weakness and wasting may be evaluated objectively by dynamometry and compound ultrasound imaging. We have measured the voluntary isometric strength of the quadriceps muscles of healthy women in their 70s (n= 25) and in their 20s (n= 25) and have compared it with the mid‐thigh cross‐sectional area of the same muscles.

The effect of high-resistance training on the strength and cross-sectional area of the human quadriceps.

Abstract. Seventeen volunteers performed unilateral strength‐training of the quadriceps with high‐resistance, low‐repetition, dynamic exercise, thrice weekly for an average of 5 weeks. Both before and after the training period, bilateral measurements were made of isometric quadriceps strength, quadriceps cross‐sectional area (by ultrasound scanning), and thigh circumference.

Comparison of serum cardiac specific troponin-I with creatine kinase, creatine kinase-MB isoenzyme, tropomyosin, myoglobin and C-reactive protein release in marathon runners: cardiac or skeletal muscle trauma?

Abstract. Problems arise in distinguishing skeletal from cardiac muscle trauma on the basis of serum enzyme tests following severe muscle exercise. The contributions of cardiac and skeletal sources have been assessed in eleven marathon runners by measuring pre‐and post‐race serum levels of cardiac‐specific myofibrillar troponin‐I together with total creatine kinase, creatine kinase‐MB isoenzyme, myoglobin, myofibrillar tropomyosin and C‐reactive protein. Total creatine kinase, creatine kinase‐MB isoenzyme, tropomyosin and myoglobin were significantly elevated above prerace levels in all runners between 1 h and 128 h post‐race. Neither mean cardiac troponin‐I nor C‐reactive protein was elevated post‐race. Nine out of sixty‐three samples fulfilled conventional positive criteria for cardiac muscle damage on the basis of combined creatine kinase and creatine kinase‐MB isoenzyme levels. Six runners had one or more positive samples. No samples had levels above twice the upper normal limit for either cardiac troponin‐I or C‐reactive protein. Correlation analysis of levels in each sample indicated skeletal and not cardiac muscle as the source of raised serum protein.

Effects of joint pathology on muscle.

The muscle wasting associated with joint damage may be highly selective; knee disorders produce quadriceps wasting but little change in the size of the hamstrings. This causes isolated quadriceps weakness, so predisposing to a position of knee flexion. Nociceptors and other receptors in and around the joint can have flexor excitatory and extensor inhibitory actions. At the knee, these receptors are likely to excite hamstrings and inhibit quadriceps. Although other actions could occur, quadriceps inhibition may be favored by a position of knee extension. Quadriceps inhibition will weaken voluntary contraction, reduce tone, and contribute to wasting of the muscle, further predisposing to a position of knee flexion. The potency of quadriceps inhibition may be considerable, even in the absence of perceived pain. A small, apparently trivial effusion (or even a clinically undetectable effusion) may cause important inhibition. In order to improve the orthopedists ability to prevent flexion contracture of the injured or operated joint, he must look not only for ways of reducing joint pain, but also for ways of preventing activity in other joint afferents. For example, he must consider the possible effects of joint position, intraarticular pressure, suture-line tension, and afferent blockade.

Measurement of Quadriceps Cross–sectional Area by Ultrasonography: A Description of the Technique and its Applications in Physiotherapy

The effect of physiotherapy on muscle growth can be evaluated by direct measurements of the individual muscle concerned, eg. using ultrasound B-scanning. The technique is suitable for adoption by physiotherapists to use independently or in collaboration with specialists in diagnostic imaging. Details of the technique are described, and the difficulties met while making and interpreting the scans are discussed. The purpose of this paper is to stress the importance of muscle-size measurements and to encourage physiotherapists to use ultrasound scanning to obtain them.