Biomechanical analysis of stresses to the fifth metatarsal bone during sports maneuvers: implications for fifth metatarsal fractures.

Fifth metatarsal stress fractures are an increasing problem in elite and recreational athletic populations. One possible mechanism of injury is the many bending moments applied to the fifth metatarsal during dynamic sports maneuvers involving rapid changes in direction and speed. A potentially important bending moment is loading of the base versus the head of the fifth metatarsal, which tends to cause a bending moment along the bone. To determine which maneuver applies the greatest pressure differential between the base and head of the fifth metatarsal, 10 college-aged male athletes performed running straight, jump take-off, jump landing, cutting right, cutting left, and accelerating while plantar pressures were recorded using a Pedar insole system (Novel Electronics, Inc., St. Paul, MN). Peak pressure at the fifth metatarsal base was subtracted from the peak pressure at the fifth metatarsal head to obtain the fifth metatarsal pressure differential-a corollary to the bending moment. The greatest fifth metatarsal pressure differential was observed during acceleration maneuvers (20 + or - 13.1 N/cm(2); P < 0.0001) followed by running straight (11.6 + or - 8 N/cm(2); P < 0.0008). The other maneuvers had low pressure differentials: jump take-off (4.2 + or - 10.6 N/cm(2)), jump landing (3.7 + or - 9.2 N/cm(2)), cutting left (2.3 + or - 4.2 N/cm(2)), and cutting right (-2.1 + or - 10 N/cm(2)). It appears that acceleration maneuvers may apply the largest bending moments to the fifth metatarsal and could lead to stress fractures. Because fifth metatarsal stress fractures are associated with rapid increases in training volume, reducing the number of acceleration events may be effective in altering the balance between bone resorption and bone formation and reducing stress fracture risk. Careful planning of training programs allowing for adequate rest between intense bouts of exercise involving many acceleration maneuvers may be the best preventative measure.

Regional foot pressure during running, cutting, jumping, and landing.

BACKGROUND: Evaluating shoes during sport-related movements may provide a better assessment of plantar loads associated with repetitive injury and provide more specific data for comparing shoe cushioning characteristics. HYPOTHESIS: Accelerating, cutting, and jumping pressures will be higher than in straight running, differentiating regional shoe cushioning performance in sport-specific movements. STUDY DESIGN: Controlled laboratory study. MATERIALS AND METHODS: Peak pressures on seven anatomic regions of the foot were assessed in 10 male college athletes during running straight ahead, accelerating, cutting left, cutting right, jump take-off, and jump landing wearing Speed TD and Air Pro Turf Low shoes (Nike, Beaverton, Ore). Pedar insoles (Novel, Munich, Germany) were sampled at 99 Hz during the 6 movements. RESULTS: Cutting and jumping movements demonstrated more than double the pressure at the heel compared with running straight, regardless of shoe type. The Air Pro Turf showed overall lower pressure for all movement types (P<.0377). Cutting to the left, the Air Pro Turf shoe had lower heel pressures (36.6 +/- 12.5 N/cm(2)) than the Speed TD (50.3 +/- 11.2 N/cm(2)) (P<.0001), and the Air Pro Turf had lower great toe pressures than the Speed TD (44.8 +/- 8.1 N/cm(2) vs 54.4 +/- 8.4 N/cm(2); P= .0002). The Air Pro Turf also had significantly lower pressures than the Speed TD at the central forefoot during acceleration (38.2 +/- 8.3 N/cm(2) vs 50.8 +/- 7.4 N/cm(2); P<.0001). CONCLUSION: Sport-related movements load the plantar surface of the foot more than running straight. Shoe cushioning characteristics were more robustly assessed during sport-related movements (4 significant results detected) compared with running straight (1 significant result detected). CLINICAL RELEVANCE: There is an interaction between shoe cushioning characteristics and sport-related movements that may influence plantar pressure and repetitive stress injuries.

(S)-(+)-1-(2-Bromo-phen-yl)ethanol.

The title compound, C(8)H(9)BrO, crystallizes with two mol-ecules in the asymmetric unit. The structure displays O-H⋯O hydrogen bonding, generating zigzag chains evolving around a screw axis along [100].