1. Strength Increase after Whole Body Vibration Compared with Resistance training. Christophe Delecluse, Sabine Verschueren, Machteld Roelants Faculteit Lichamelijke Opvoeding en Kinesitherapie Katholieke Universiteit Leuven België

2. WBV-training: positive influence on muscle strength? n Lack of scientific support n Mechanism: vibration stimulus stimulation sensory receptors in muscle (presumably muscle spindles) activation alpha motor neurons activation alpha motor neurons Tonic vibration reflex leading to muscle contraction: stimulus for increase in strength?

3. Studies acute effects WBV Bosco et al. 1999 (Clin Physiol): volleyball players, increase in strength-speed, strength-power leg press Bosco et al. 2000 (Eur J Appl Physiol): team sports, 7% increase mechanical power knee-extensors (leg press), 3,8% increase jump height Torvinen et al. 2002 (Clin Physiol & Func Im): 3,2% increase isometric strength knee-extensors, 2,5% increase jump height Torvinen et al. 2002 (Int J Sports Med): no effects on isometric strength knee- extensors, jump height

4. Bosco et al. 1998 (Biol of Sport): physically active subjects, 10 days WBV- training, 6,1% increase in power, 12% increase jump height Runge et al. 2000 (J Musculoskel Neuron Interact): elderly subjects, 2 months WBV-training, 18% increase in ‘chair rising time’ Torvinen et al. 2002 (Med Sci Sports and Exc): untrained subjects, 4 months WBV-training, 8,5% increase jump height, 2,5% increase isometric strength knee-extensors De Ruiter et al. 2002 (Geneeskunde en Sport): physically active subjects,no improvement in isometric and explosive strength knee-extensors No unambiguous results: –Differences in training schedules, group composition, physical condition –No placebo group –No comparison to regular resistance training Long term WBV studies

5. Purpose of this study n long term study: –Investigate effects on isometric strength knee-extensors of exercises performed on platforms with and without vibration (placebo) –Compare effects to resistance training of moderate intensity (10-20RM)

6. Method n 67 young ladies (21,4±1,8 jaar) n untrained n 4 groups (random) WBV group, N=18 Placebo group (PL), N=19 Resistance group (RES), N=18 Control group (CO), N=12 n 12 weeks, 3 x/week (36 sessions)

7. WBV group PL group Static and dynamic exercises for knee-extensors: squat, deep squat, one legged squat, lunge,... WBV group PL group Static and dynamic exercises for knee-extensors: squat, deep squat, one legged squat, lunge,... n Vibration platform (Power Plate®) (Power Plate®) n progressive increase in intensity and volume –35-40Hz / 2,5-5,0mm –2,28 - 5,05g –Total vibration time per session: 3-20 min –rest period: 60-5 sec n Placebo platform - equal platform not resulting in increased muscle contraction - amplitude negligible - acceleration only 0,4g

8. EMG activity in the m. rectus femoris (high squat) VIBRATION 35 Hz

9. EMG activity in the m. gastrocnemius

10. Resistance-training group Resistance-training group n University fitness centre n 20 min warm up: bicycle, step, treadmill n Resistance training schedule with moderate intensity for knee-extensors (Kraemer 2002, ACSM) n leg press, leg extension (Technogym®): 2 sets W1 W3 W6 W9W12 20 RM 15 RM12 RM 10RM

11. Pre-post measuring n Iso-kinetic dynamometer (REV9000, Technogym®) n maximum voluntary isometric strength knee-extensors (angle in knee: 130°) n post-test: min. 72 hours after last training session

12. Results (1) ISO † 110 130 150 170 190 210 230 KR N=18 WBV N=18 PL N=19 CO N=12 Group Knee-extensor moment (N.m) pre post **

13. Results (2) n Isometric strength –significant interaction effect (group x time) n F (3)=15,94; P<0.001 (ANOVA for repeated measurements) – significant increase (P<0.001) pre-post (contrast analysis): n in WBV group: 16,6 ± 10,8% n in RES group: 14,4% ± 5,3% – no significant difference (P>0.05) pre-post: n in PL group: 3,8 ± 11,4 % n in CO group: -7,3 ± 15,9%

14. Causes of strength gain n Hypothesis: strength gain after 12 weeks WBV mainly due to neural adaptations ~ resistance training (Enoka 1997, J Biomech) –extensive sensory stimulation: possible more efficient use of sensory information in production of strength n input of proprioceptors (Ia, IIa, Ib) is used in building up isometric strength (Gandevia 2001, Physiol Rev)

15. Conclusions (1) n The muscle contractions during WBV efficient stimulus for strength gain in knee extensors in untrained subjects n Torvinen et al. 2002: –only 3,7% increase in strength in knee-extensors after 2 months WBV-training  placebo effect this study –this study: 16,6% Difference in training schedule: time, volume, intensity,… ‘full motor unit activation’ leads to fatigue in motor units = stimulus to strength gain (Sales 1987, Exerc Sport Sci Rev)

16. Conclusions (2) n 12 weeks WBV training with untrained ladies: –Strength gain in knee-extensors comparable to resistance training of moderate intensity (10-20RM) –effect not attributable to stance or exercises on platform but to increased muscle activity (EMG) during WBV n NO placebo-effect

17. n Strength gain following 12 weeks of whole body vibration training –C. Delecluse, M. Roelants, S. Verschueren n Published in Medicine and Science in Sports and Exercise Vol.35, No.6, pp. 1033-1041, 2003