Navigational strategies during fast walking: a comparison between trained athletes and non-athletes.

Many common activities such as walking in a shopping mall, moving in a busy subway station, or even avoiding opponents during sports, all require different levels of navigational skills. Obstacle circumvention is beginning to be understood across age groups, but studying trained athletes with greater levels of motor ability will further our understanding of skillful adaptive locomotor behavior. The objective of this work was to compare navigational skills during fast walking between elite athletes (e.g. soccer, field hockey, basketball) and aged-matched non-athletes under different levels of environmental complexity in relation to obstacle configuration and visibility. The movements of eight women athletes and eight women non-athletes were measured as they walked as fast as possible through different obstacle courses in both normal and low lighting conditions. Results showed that athletes, despite similar unobstructed maximal speeds to non-athletes, had faster walking times during the navigation of all obstructed environments. It appears that athletes can process visuo-spatial information faster since both groups can make appropriate navigational decisions, but athletes can navigate through complex, novel, environments at greater speeds. Athletes' walking times were also more affected by the low lighting conditions suggesting that they normally scan the obstructed course farther ahead. This study also uses new objective measures to assess functional locomotor capacity in order to discriminate individuals according to their level of navigational ability. The evaluation paradigm and outcome measures developed may be applicable to the evaluation of skill level in athletic training and selection, as well as in gait rehabilitation following impairment.

Changing hormone levels during the menstrual cycle affect knee laxity and stiffness in healthy female subjects.

BACKGROUND: Whether knee laxity varies throughout the menstrual cycle remains controversial. As increased laxity may be a risk factor for anterior cruciate ligament (ACL) injury, further research is warranted. HYPOTHESIS: Variation in estradiol and progesterone levels during the menstrual cycle influences knee laxity and stiffness. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: The serum estradiol and progesterone levels of 26 healthy female subjects were recorded in the follicular phase, ovulation, and the luteal phase. Knee joint laxity was assessed using a standard knee arthrometer at the same intervals. Stiffness changes in the load-displacement curve were determined. Hormone levels across the cycle were compared between responders and nonresponders, defined by whether changes in knee laxity at 89 N occurred. RESULTS: Greater laxity at 89 N during ovulation was observed (ovulation: 5.13 +/- 1.70 mm vs luteal: 4.55 +/- 1.54 mm, P = .012). In knee laxity testing at manual maximum load, greater laxity was noticed during ovulation (14.43 +/- 2.60 mm, P = .018), as compared with the follicular phase (13.35 +/- 2.53 mm). A reduction in knee stiffness of approximately 17% (ovulation: 12.48 +/- 5.46 N/mm vs luteal: 15.02 +/- 7.71 N/mm, P = .042) during ovulation was observed. However, there were no differences in hormone levels between responders and nonresponders at 89 N. CONCLUSION: Female hormone levels are related to increased knee joint laxity and decreased stiffness at ovulation. To understand subject variations in knee joint laxity during the menstrual cycle in female athletes, further investigation is warranted.

Cane-assisted gait biomechanics and electromyography after total hip arthroplasty.

OBJECTIVE: To quantify the effects of cane use during walking on hip joint kinematics, kinetics, and muscle activity patterns after unilateral total hip arthroplasty (THA). DESIGN: Nonrandomized experimental design. SETTING: Urban inpatient hospital. PARTICIPANTS: Adults (n=9 men, 2 women) with no history of orthopedic or neuromuscular disease who underwent elective unilateral THA. INTERVENTION: Gait was assessed preoperatively and 4 and 8 months postoperatively. MAIN OUTCOME MEASURES: Three-dimensional hip joint motion and moments and electromyographic patterns of gluteus medius, tensor fascia latae, lateral hamstring, and vastus lateralis were measured during level walking, with and without use of a straight cane. RESULTS: When a cane was held in the contralateral hand, the abduction moment of the affected hip decreased by 26%, whereas that of the contralateral hip increased by 28%. Use of a cane in THA rehabilitation is important because it reduces the load on the operative hip so that bone and soft tissues can heal. Our results suggest that load reduction was successful on the operative side, but the loads on the contralateral side were increased. CONCLUSIONS: After unilateral arthroplasty, subjects using a cane had increased hip abduction moments on the nonoperative hip and decreased hip abduction moments on the operative hip. Clinicians should be mindful of the effects of cane use on the contralateral hip.