Interleukin-6 and Delayed Onset Muscle Soreness Do Not Vary During the Menstrual Cycle

The purpose of this study was to determine if a difference in interleukin-6 (IL-6) and delayed onset muscles soreness (DOMS) exists in two different phases of the menstrual cycle. Nine runners performed one 75-min high-intensity interval running session during the early follicular (EF) phase and once during the midluteal (ML) phase of the menstrual cycle. Estrogen and progesterone levels were significantly reduced in the EF phase when compared to the ML phase. IL-6 levels increased from pre- to postexercise in the EF and ML phases (p < .001). There was no relationship between the IL-6 level and DOMS. The results suggest that menstruating female runners need not vary training throughout the month to reduce DOMS.     

Skeleton Changes Induced by Horse Riding on Medieval Skeletal Remains from Croatia

Skeletal remains of 35 individuals from the Croatian excavation site Kamen Most – Kaldrma from the fourteenth to fifteenth centuries were analyzed anthropologically. Due to specific skeletal characteristics, eight of them were analyzed in great detail in this study. The results of additional analysis indicated that all bone elements, except pelves, of all eight persons belonged to males. All pelvic girdle have characteristics of female sex and pronounced muscle attachments that are both indicative of horse riding. All eight persons had at least two of six changes on femora indicative of horse riding. Vertebrae of seven persons (one person did not have preserved vertebrae) have Schmorl's nodes. Signs of advanced osteoarthritis were found on all joints in all eight persons. All of them also have visible signs of periostitis especially on lower extremities. Pathological signs of trauma were found in five persons. Two of them had skull fractures and the rest had fractures of extremities which are also characteristic for horse riders. The average age of all eight persons was above 45 years at death. DNA analysis confirmed male sex for seven individuals. The results were additionally confirmed by later archeological findings of tombstones with illustrations of horse riders.     

Book reviews

Clinical sports medicine, Robert C. Cantu, (ed.), The Collamore Press, Lexington, Massachusetts, Toronto, 1984. 219 pp, £19.95 (hb), ISBN 0 669 06842 X

Sports injuries, a self‐help guide, Vivian Grisogono, John Murray Ltd, London, 1984. 293 pp, £7.95 (hb), ISBN 0 7195 4111 5

Athletes’ guide to mental training, Robert N. Nideffer, Human Kinetics, Champaign, Illinois (distributed in the UK by Eddington Hook & Co.) 1985. vii +156 pp, $9.95 (pb), ISBN 0 931250 96 X

Scientific foundations of coaching, R.R. Pate, B. McClenaghan and R. Rotella, Saunders College Publishing, Philadelphia, 1984. xii + 344 pp, £21.95(hb), ISBN 0 03 057961 9

Mathematics in sport, M. Stewart Townend, Ellis Horwood, Chichester, 1984. 202 pp (hb), ISBN 0 85312 717 4

Frontiers of exercise biology, ’Big Ten Body of Knowledge’ symposium series, Vol. 13 K.T. Borer, D.W. Edington and T.P. White (eds), Human Kinetics Publishers Inc., Champaign, Illinois, (distributed in the UK by Edington Hook & Co.), 1983. vii + 295 pp, $31.95(hb), ISBN 0 931250 49 8

The knee, Philippe Segal and Marcel Jacob, Wolfe Medical Publications, Frome, Somerset, 1984. 143 pp (hb), £15, ISBN 2 224 00887 2

Psychological foundations of sport, J.M. Silva and R.S. Weinberg (eds), Human Kinetics, Champaign, Illinois, (distributed in the UK by Eddington Hook & Co), 1984. xxiv + 528 pp, £22.50 (hb), ISBN 0 93 1250 59 5

Physical activity and the social sciences, W. Neil Widmeyer, Mouvement Publications Inc., Ithaca, 1983. 472 pp, £9.00 (pb), ISBN 0 932392 13 X     

Increased dietary carbohydrate and endurance during single‐leg cycling using a limb with normal muscle glycogen concentration

The purpose of this study was to test the hypothesis that increased availability of blood‐borne glucose would improve endurance after carbohydrate loading. A single‐leg exercise model was employed, taking advantage of the fact that supercompensation of muscle glycogen occurs only in a previously exercised limb. Endurance time to exhaustion at 70% of maximal oxygen uptake (VO₂max) was determined for 11 males and three females who were then allocated to a control group or a high‐carbohydrate (CHO) group. For 3 days following Test 1 the control group maintained a prescribed normal diet whilst the CHO group increased the proportion of energy derived from carbohydrate (62.1 ± 4.3% cf. 43.9 ± 2.0%, P < 0.01). The endurance test was then repeated using the leg that was inactive during Test 1. Endurance time was increased on Test 2 (123.7 ± 43.2 min cf. 98.5 ± 21.9 min, P <0.05 one‐tailed test) for the CHO group but not for the control group (101.8 ± 21.7 min cf. 107.5 ± 9.1 min, NS). There was no indication of enhanced carbohydrate metabolism during Test 2 for the CHO group but mean heart rate was lower during Test 2 than during Test 1 (145 ± 14 beat min ^‐1 cf. 152 ± 12 beat min ^‐1, P<0.05). These results suggest that the prior consumption of a high‐carbohydrate diet improves endurance during high‐intensity cycling with a limb with normal muscle glycogen concentration.     

Characteristics of the start in women's World Cup skeleton

This study characterizes key elements of the start in elite female World Cup skeleton athletes. The top 20 female competitors in three World Cup races were videotaped within a calibrated space to allow the following components of the start to be quantified: (1) acceleration (velocity at 15-m mark, time to 15-m mark), (2) capacity (time to load, total number of steps to load), and (3) load (velocity at 45-m mark). A correlation analysis was used to establish the relationship between the variables of interest and overall start time (15- to 65-m mark). Velocity at the 15-m mark accounted for 86% of the variance in overall start time at St. Moritz and 85% at Sigulda. A stepwise regression analysis revealed that approximately 89% of the variation in start time could be explained by velocity at the 15-m mark, time to load, and velocity at the 45-m mark. Of the variables analysed in this study, rapid acceleration to attain a high velocity at the 15-m mark was the most important component of a fast overall start time. The importance of the time to load and velocity at the 45-m mark vary according to the different track characteristics.     

A toy model that predicts the qualitative role of bar bend in a push jerk

In this work, we describe a simple coarse-grained model of a barbell that can be used to determine the qualitative role of bar bend during a jerk. In simulations of this model, we observed a narrow time window during which the lifter can leverage the elasticity of the bar in order to lift the weight to a maximal height. This time window shifted to later times as the weight was increased. In addition, we found that the optimal time to initiate the drive was strongly correlated with the time at which the bar had reached a maximum upward velocity after recoiling. By isolating the effect of the bar, we obtained a generalized strategy for lifting heavy weight in the jerk.     

Effect of the coefficient of friction of a running surface on sprint time in a sled-towing exercise

This study investigated the effect of the coefficient of friction of a running surface on an athlete's sprint time in a sled-towing exercise. The coefficients of friction of four common sports surfaces (a synthetic athletics track, a natural grass rugby pitch, a 3G football pitch, and an artificial grass hockey pitch) were determined from the force required to tow a weighted sled across the surface. Timing gates were then used to measure the 30-m sprint time for six rugby players when towing a sled of varied weight across the surfaces. There were substantial differences between the coefficients of friction for the four surfaces (μ = 0.21–0.58), and in the sled-towing exercise the athlete's 30-m sprint time increased linearly with increasing sled weight. The hockey pitch (which had the lowest coefficient of friction) produced a substantially lower rate of increase in 30-m sprint time, but there were no significant differences between the other surfaces. The results indicate that although an athlete's sprint time in a sled-towing exercise is affected by the coefficient of friction of the surface, the relationship relationship between the athlete's rate of increase in 30-m sprint time and the coefficient of friction is more complex than expected.     

Shoulder 3D range of motion and humerus rotation in two volleyball spike techniques: injury prevention and performance

Repetitive stresses and movements on the shoulder in the volleyball spike expose this joint to overuse injuries, bringing athletes to a career threatening injury. Assuming that specific spike techniques play an important role in injury risk, we compared the kinematic of the traditional (TT) and the alternative (AT) techniques in 21 elite athletes, evaluating their safety with respect to performance. Glenohumeral joint was set as the centre of an imaginary sphere, intersected by the distal end of the humerus at different angles. Shoulder range of motion and angular velocities were calculated and compared to the joint limits. Ball speed and jump height were also assessed. Results indicated the trajectory of the humerus to be different for the TT, with maximal flexion of the shoulder reduced by 10 degrees, and horizontal abduction 15 degrees higher. No difference was found for external rotation angles, while axial rotation velocities were significantly higher in AT, with a 5% higher ball speed. Results suggest AT as a potential preventive solution to shoulder chronic pathologies, reducing shoulder flexion during spiking. The proposed method allows visualisation of risks associated with different overhead manoeuvres, by depicting humerus angles and velocities with respect to joint limits in the same 3D space.     

Effect of exercise and nasal splinting on static and dynamic measures of nasal airflow

The main aim of this study was to assess the separate and combined effects of exercise and nasal splinting on static and dynamic measures of nasal airflow. In a randomized crossover design, 12 healthy participants (6 men, 6 women) performed static and dynamic spirometric nasal airflow assessment tests, with or without nasal splinting (Breathe-Right?), before and after a maximal oxygen uptake (VO 2max ) treadmill test. At least 7 days later, the V O 2max and nasal airflow tests were repeated. The results showed that the measured variables were not significantly different with and without nasal splinting. We conclude that the absence of significantly enhanced nasal patency observed for nasal splinting and after exercise suggest that these factors have a minimal impact on nasal airflow volume and rate.     

Fluid ingestion and exercise hyperthermia: Implications for performance,thermoregulation, metabolism and the development of fatigue

The development of fatigue during exercise and the subsequent onset of exhaustion occur earlier in the heat than in cooler environments. The underlying mechanisms responsible for the premature development of fatigue in the heat have yet to be clearly identified. However, the proposed mechanisms include metabolic, cardiovascular and central nervous system perturbations, together with an elevated core temperature. Fluid ingestion is one of three strategies that have been shown to be successful in enhancing the performance of endurance exercise in the heat, with the other interventions being precooling and acclimatization. However, like the development of fatigue in the heat, the mechanisms by which fluid ingestion allows for improved exercise performance remain unclear. We propose that fluid ingestion enhances exercise performance in the heat by increasing the heat storage capacity of the body. We suggest that the thermoregulatory, metabolic and cardiovascular alterations that occur as a result of this increased heat storage capacity contribute to performance enhancement when fluid is ingested during exercise heat stress.