Dr Mel Siff Blog

This following reference should make some interesting reading for those who
are vehemently opposed to the idea of plyometric training on the basis of it
“causing injuries”. In fact, this article indicates that properly prescribed
plyometric exercises can offer significant benefits over normal sporting
activities.

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Witzke KA & Snow CM Effects of plyometric jump training on bone mass in
adolescent girls. Med Sci Sports Exerc 2000 Jun; 32(6):1051-7

PURPOSE: The purpose of this study was to investigate the effects of 9 months
of plyometric jump training on bone mineral content (BMC), lower extremity
performance, and static balance in adolescent girls METHODS: Exercisers
trained 30-45 min, three times per week, performing various exercises using
weighted vests (squats, lunges, calf raises) and plyometrics (hopping,
jumping, bounding, and box depth jumps). The program was designed to load the
lower extremities. Control subjects, matched to exercisers for age and months
past menarche, maintained their usual activities. The following were assessed
at baseline and 9 months: BMC, strength by isokinetic dynamometry, power
(Wingate test), and static balance. . . .

RESULTS: ….Both groups experienced a significant increase in percent change
in bone mass compared to zero, for the whole body (mean: 3.7% for exercisers,
3.6% for controls), femoral neck (4.5% vs 2.4%), lumbar spine (L2-4) (6.6% vs
5.3%), and femoral shaft (3.4% vs 2.3%), but only the exercisers improved BMC
of the greater trochanter (3.1% vs 1.9%). Furthermore, the exercise group
significantly improved knee extensor strength (14.7% vs 7.3%) and
medial/lateral balance (38.1% vs 9.5%), whereas the control group
demonstrated no changes. The variety of lateral movement activities performed
by the exercise group may have contributed to the differences observed
between groups for greater trochanter bone mineral density (BMD), leg
strength, and medial/lateral balance.

CONCLUSION: The trends observed in bone mass between groups suggest that
plyometric jump training continued over a longer period of time during
adolescent growth may increase peak bone mass.

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Dr Mel C Siff
Denver, USA

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Tags: Bmc, Bone Mass, Bone Mineral Content, Bone Mineral Density, Dr Mel Siff, Jump Training, Lower Extremities, Lumbar Spine, med sci spo ex, medicine and science in sport and exercise, plyometric, plyometrics, Supertraining, Weighted Vests