Soreness in lower extremities and back is reduced by use of shock absorbing heel inserts.

Soccer referees participating in large soccer tournaments may develop overuse injuries. In this study the effect of shock absorbing heel inserts in the incidence of soreness was investigated. Forty-eight referees were randomly selected to wear shock absorbing heel inserts (SAH) in the 5 day-tournament, while 43 referees were the control group. A daily questionnaire inquiring about complaints from the locomotive system was completed for each referee and in case of any soreness they were examined by doctors to document and classify the anatomical site. Calf, thigh, back, achilles tendon and knee were the most common localizations of overuse symptoms. The incidence of soreness in achilles tendon, calf and back were significantly reduced by the use of (SAH) inserts.

Menstrual patterns in Danish elite swimmers.

Questionnaires were given to 140 female elite swimmers from the highest ranking division in the Danish Swimming Association inquiring about their menstrual history. Eighty-nine percent completed the questionnaires. We found a very low incidence of menstrual dysfunction (16%) compared to other groups of endurance trained females. Hard physical endurance training did not seem to delay the onset of menarche among swimmers. Furthermore, no difference in adjusted body mass between a group with oligomenorrhoea and a normal menstruating group could be demonstrated. The study indicated that the influence of body mass or body fat content was a more important factor in menstrual function than the amount of training or psychological stress.

Plasma atrial natriuretic peptide in elite runners.

Plasma atrial natriuretic peptide (ANP) was measured in relation to a 5-km race in 11 elite mid- and long-distance runners. Plasma ANP, measured in relation to the race, was compared with the relative changes in plasma volume and the physical fitness of the runners. Relative changes in plasma volume were estimated by changes in hemoglobin and hematocrit, and physical fitness was evaluated by a cycle ergometer test, running time, and resting heart-rate. In connection with the race, plasma ANP increased in all the runners. Median plasma ANP was 4.7 pmol.l-1 before the race and 12.9 pmol.l-1 immediately after the race. No correlation was found between the changes in ANP and the relative changes in plasma volume or the measurements of physical fitness. A volume expansion of the red blood cells was found immediately after the race. We conclude that well-conditioned subjects have a prominent rise in plasma ANP, in spite of a high maximal cardiac output.

Altered timing of hamstring muscle action in anterior cruciate ligament deficient patients.

Recent studies indicate that the hamstrings are essential antagonists in ACL deficient patients. In order to evaluate muscle coordination under physiologic conditions, nine patients with arthroscopically verified total ACL ruptures were compared with nine control volunteers. This comparison was made from electromyograms of the thigh muscles and heel contact recordings made while walking on a treadmill. While walking on a horizontal level, the patient's muscle activity did not differ from controls, but when the knee load was increased by walking uphill, the hamstring muscles in patients were activated significantly earlier than among controls. It is proposed that an altered muscle coordination is probably essential in ACL deficient patients to secure knee stability. This study suggests a new approach to investigate the coordination of muscles under physiologic conditions in ACL deficient patients, and may guide rehabilitation programs in the future.

Reduced strength of skin in Ehlers Danlos syndrome, type III.

The biochemical properties, ratio collagen type I/type III and the pattern of reducible collagen crosslinks were studied in skin biopsy samples from 10 patients with Ehlers Danlos syndrome type III (ED III) and 10 age- and sex-matched controls. The ED III patients had marked reductions in skin strength and stiffness (42% and 22%, respectively). The ultimate extensibility of the skin, however, was not different from that of the controls. Consequently, a certain load applied to the skin of these patients results in greater deformation than in that of the controls, due to reduced stiffness. The bursting limit is no different from that of the controls. Thus the skin in the ED III patients is not hyperextensible, it merely has reduced strength and stiffness. The reduction in strength could not be explained by differences in skin thickness or collagen content. Skin thickness, collagen content and ratio collagen type I/type III were the same as in the controls, as also was the pattern of reducible collagen crosslinks. These alterations in the mechanical properties of the skin of patients with ED III may be attributable to the molecular structure of the mature collagen or the arrangement of the collagen fibres.

Passive tension of the ankle before and after stretching.

The passive tension resulting from dorsiflexion of the ankle was measured in relation to stretching in six handball players and six soccer players. Corresponding values of ankle angle and passive tension were measured by a strain gauge and a potentiometer connected to a pedal system. The passive tension versus ankle angle was measured before and 90 minutes after a single contract-relax stretching program of the plantar flexors. Stretching lowered the passive tension by up to 18%. Contract-relax stretching performed twice a day for 3 weeks lowered the passive tension in the plantar flexors by up to 36%. Before the last measurements, no stretching was performed for 20 hours or more. Stretching thus had both a short-term effect, matching the length of a training session, and a long-term effect, shown in a reduction of passive tension after 3 weeks. The relative decrease in passive tension after stretching exercises was constant from a neutral position of the ankle to maximal dorsiflexion. There was no correlation between 1) flexibility and the short-term effect of stretching, 2) flexibility and the long-term effect of stretching, or 3) the short-term and long-term effects of stretching. This indicates that passive tension was decreased in all subjects irrespective of their flexibility, and that subjects who had short-term effects after stretching did not necessarily demonstrate a long-term effect.

Biomechanical properties of the human ankle in relation to passive stretch.

Viscous/plastic properties were investigated in the passive tissue opposing dorsiflexion of the human ankle. The foot was rotated (dorsiflexed) and fixed. Due to viscous/plastic properties, the passive torque declined with time. After 300 s, torque, relative to the initial torque at 0 s, had fallen by 22.7% +/- 2.6% (mean +/- 1S.D.), as an expression of the relative importance of the viscous/plastic tissue properties for the passive torque. By a peel-off technique the number of different tissue elements with viscous/plastic properties was found to be at least three. After 100 s, all but one of these elements had yielded completely. Viscous/plastic properties were unchanged by stretching when measured 90 min after a single stretching program and when measured 24 h after stretching procedures had been performed twice a day for three weeks.