european college of sport science

OP-BM03 Biomechanics 3
differences were due to lower increments in RBC [La] (-16% W vs. I & -10% E vs. I). No significant differences were found for the increments
of plasma, RBC & ratio in the following time intervals.
The peak power (PP) output as well as the mean power (MP) output for the sprint test was significantly lower for W (MP: 680 ± 181 Watt)
compared to E & I (MP: 738 ± 192 Watt; E) (MP: 740 ± 191 Watt; I).
Discussion: Several possible effects of WU are discussed in literature which might have an effect on performance. In the present study we
tested if different warming up intensities influence the lactate flux across the RBC membrane. A recent study from our group has shown
that MCT in RBC might be translocated from cytoplasm to the membrane in response to exercise, which might effect La flux. In the present
study the WU had no influence on La flux across the RBC membrane. The increase in plasma [La] was significantly lower in the first time
interval for “I”. Therefore one would expect a similar or even higher increase in RBC [La] (and not a lower) because of a less stressed
transport system. But may be it must be considered, that the pre-loading of RBC with lactate and therefore the [La] gradient is different
between the conditions. It can be speculated, that the time (of warming up) was too short to induce a translocation of MCT. Further molecular
investigations are needed to identify possible mechanisms for translocation of MCT.
THE EFFECTS OF 15-WEEKS HOCKEY SPECIFIC TRAINING ON SKELETAL HEALTH AND BODY COMPOSITION IN ACTIVE
WOMEN
WALLACE, J.A., REILLY, T., GEORGE, K.
ABERYSTWYTH UNIVERSITY
Introduction: The importance of sport and exercise for optimizing body composition and bone health in women is well documented
(Drinkwater et al., 1995). Although evidence from former athletes suggests that any training-induced anabolic skeletal effect achieved,
disappears after the cessation of an athletic career (Karlsson et al., 2000 and 1996). There is a lack of information about bone health in
relation to seasonal changes in training and the overall long-term health benefits in active women. The aim of this investigative study was
to establish whether 15 weeks of hockey-specific training and match-play had a beneficial effect on bone mineral density and body
composition in active pre-menopausal women.
Method: Body composition (total mass, fat mass, lean mass, and percent body fat) and whole-body, proximal femur and lumbar spine
bone mineral density (BMD), of 12 female club-level hockey players (32.8 ± 7.8 years; 58.7 ± 5.0 kg; 1.64 ± 0.04 m) and 13 normo-active
controls (32.9 ± 7.1 years; 59.3 ±6.6 kg; 1.63 ± 0.05 m), were measured using dual-energy X-ray absorptiometry (DXA). Measures were
taken pre-season and before the mid-season break, 15-weeks apart. Training consisted of 2.5 hours of hockey-specific fitness work,
plyometrics, drills and practices and a 70-minute match each week, in addition to their normal physical activity. Data were analysed
using SPSS v14, by means of a 2-way mixed model design ANOVA.
Results: The hockey players had significantly greater (P < 0.05) proximal femur BMD (trochanter and inter-trochanter) at baseline compared
to the controls; all other body composition variables were not significantly different. After 15 weeks of training the hockey players
had a significantly lower percent body fat (P < 0.05) and significantly greater lumbar spine BMD (L1, L2, L3 and L4) and proximal femur
BMD (neck, trocahanter and intertrochanter) than the normo-active control group. The hockey players exercise duration, also significantly
increased during season (from 3.6 ± 2.3 pre-season to 6.2 ± 2.2 hours/week mid-season; P < 0.05).
Discussion: Long-term participation in hockey can improve body composition and enhance BMD at the lumbar spine and proximal
femur, by means of increasing bone mass accrual. The hockey players had 18.3 ± 8.4 years playing experience, during which sport
specific skeletal adaptions should have occurred. However, some skeletal regions (i.e. lumbar spine) still increased in BMD during the
season, demonstrating that these sites may be susceptible to transient changes in BMD due to the seasonal nature of the sport. Therefore
off-season exercise needs to be promoted, to help maintain long-term bone health in team sports.
References
Drinkwater BL, Grimston SK, Raab-Cullen DM, Snow-Harter C. (1995). Med Sci Sports Exerc, 27, i-vii.
Karlsson MK, Linden O, Karlsson C, Johnell O, Obrant K, Seeman E. (2000). Lancet, 355, 469-470.
Karlsson MK, Hasserius R, Obrant K. (1996). Calcif Tissue Int, 59, 245-248.
15:15 - 16:45
Oral presentations
OP-BM03 Biomechanics 3
THE EFFECT OF INCREASED VOLUNTARY EFFORT ON NEUROMUSCULAR CONTROL IN HIGH IMPACT LANDING
AVELA, J., PELTONEN, J., CRONIN, N., KUMPULAINEN, S., NICOL, C., LINNAMO, V., GRUBER, M.
UNIVERSITY OF JYVÄSKYLÄ
The effect of increased voluntary effort on neuromuscular control in high impact landing
Avela, J. 1, Peltonen, J.1, Cronin, N.1, Kumpulainen, S.1, Nicol, C.2, Linnamo, V.1, Gruber, M1,3
1: NMRC (Jyväskylä, Finland), 2: CNRS (Marseilles, France), 3: DTMS (Potsdam, Germany)
Leg extensor muscles have been shown to be activated well before the onset of ground contact during natural movements like running,
jumping, landing etc. In landing tasks the motor system has to adjust pre-landing activity based on the predicted impact peak in order to
achieve a safe and smooth landing (Santello 2005). Furthermore, it has been shown that in the case of very high impact loads the postimpact
response is crucial as it modifies body acceleration (Melvill Jones and Watt 1971). However, the exact mechanism that modulates
electromyographic (EMG) activity in the early post-impact phase is unclear. Both pre-programmed (Melvill Jones and Watt 1971) and reflex
(Santello and McDonagh 1998) origins have been suggested. Therefore, the purpose of the present experiment was to study the contribution
of spinal and supraspinal mechanisms during extreme landing conditions, where pre-contact activities of the leg extensor muscles
could be voluntarily varied.
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