Immediate and short-term effects of gait retraining on the knee joint moments and symptoms in patients with early tibiofemoral joint osteoarthritis: a randomized controlled trial.

OBJECTIVE: To evaluate the effectiveness of a knee adduction moment (KAM) gait retraining in patients with early knee osteoarthritis up to 6 months post-training. METHOD: We conducted a single blinded randomized controlled trial on a total of 23 patients with early knee osteoarthritis who were randomly allocated to the gait retraining group and walking exercise group. Twenty of them completed the corresponding training and the 6-month evaluation. We measured KAM, knee flexion moment (KFM) and western ontario and McMaster universities osteoarthritis index (WOMAC) osteoarthritis index before, immediate after, and 6 months after training. A repeated measures analysis of covariance (ANCOVA) was used to compare KAM, KFM and WOMAC osteoarthritis index scores across the three time points i.e., pre-training, post-training, and 6-month follow-up with gender, knee osteoarthritis severity, and pre-training KAM, KFM and WOMAC scores set as covariates. Post-hoc analyses were conducted when indicated. RESULTS: Significant time × group interactions were found for both KAM and WOMAC osteoarthritis index scores (P < 0.002). No interaction was found for KFM (P = 0.123). KAM after gait retraining was significantly lower than the pre-training value (P < 0.001) and such effect was maintained at 6-month follow-up (P = 0.01). There was no significant difference in the KAM across time in the walking exercise group (P > 0.208). WOMAC osteoarthritis index score after training and score at the 6-month follow-up were significantly improved in the gait retraining group (P = 0.001), while the WOMAC osteoarthritis index score remained similar. CONCLUSIONS: Gait retraining is an effective intervention to reduce KAM during walking and to improve the symptoms of patients with early knee osteoarthritis in short term.

Effect of foot progression angle adjustment on the knee adduction moment and knee joint contact force in runners with and without knee osteoarthritis.

BACKGROUND: Knee adduction moment (KAM) is often used as a surrogate marker of knee contact force (KCF) during walking. Previous studies have reported potential benefits to reduce KAM in patients with knee osteoarthritis (OA) by foot progression angle adjustment. However, KAM is an external moment and it does not consider any muscle contribution to the joint loading, which should pose a greater influence in running than walking. RESEARCH QUESTION: This study used a computational model to compare KAM and KCF between runners with and without knee OA during running. In addition, we evaluated the KAM and KCF when runners adjusted to an out-toe running style. METHODS: Kinematic, kinetic, and lower limb EMG data were collected from 9 runners with knee OA and 10 healthy counterparts. They were asked to run at their usual speed with standard shoes on an instrumented treadmill. RESULTS: We found no significant difference in the KAM during running between OA and the healthy group (p > 0.376). However, runners with knee OA exhibited a greater total KCF than the healthy counterparts (p < 0.041). We did not observe any reduction in KAM after foot progression angle adjustment (p > 0.346). Surprisingly, an increase in the longitudinal KCF and total KCF were found with adjustment of foot progression angle (p < 0.046). SIGNIFICANCE: Unlike the findings reported by the previous walking trials, our findings do not support the notion that foot progression angle adjustment would lead to a lower joint loading during running.

Immediate effects of modified landing pattern on a probabilistic tibial stress fracture model in runners.

BACKGROUND: Tibial stress fracture is a common injury in runners. This condition has been associated with increased impact loading. Since vertical loading rates are related to the landing pattern, many heelstrike runners attempt to modify their footfalls for a lower risk of tibial stress fracture. Such effect of modified landing pattern remains unknown. This study examined the immediate effects of landing pattern modification on the probability of tibial stress fracture. METHODS: Fourteen experienced heelstrike runners ran on an instrumented treadmill and they were given augmented feedback for landing pattern switch. We measured their running kinematics and kinetics during different landing patterns. Ankle joint contact force and peak tibial strains were estimated using computational models. We used an established mathematical model to determine the effect of landing pattern on stress fracture probability. FINDINGS: Heelstrike runners experienced greater impact loading immediately after landing pattern switch (P<0.004). There was an increase in the longitudinal ankle joint contact force when they landed with forefoot (P=0.003). However, there was no significant difference in both peak tibial strains and the risk of tibial stress fracture in runners with different landing patterns (P>0.986). INTERPRETATION: Immediate transitioning of the landing pattern in heelstrike runners may not offer timely protection against tibial stress fracture, despite a reduction of impact loading. Long-term effects of landing pattern switch remains unknown.

Facilitatory and inhibitory effects of Kinesio tape: Fact or fad?

OBJECTIVES: Kinesio tape (KT) is a commonly used intervention in sports. It claims to be able to alter the muscle activity, in terms of both facilitation and inhibition, by certain application methods. This study compared the neuromuscular activity of the wrist extensor muscles and maximal grip strength with facilitatory, inhibitory KT, and tapeless condition in healthy adults who were ignorant about KT. Potential placebo effects were eliminated by deception. DESIGN: Randomized deceptive trial. METHODS: 33 participants performed maximal grip assessment in a randomly assigned order of three taping conditions: true facilitatory KT, inhibitory KT, and no tape. The participants were blindfolded during the evaluation. Under the pretense of applying a series of adhesive muscle sensors, KT was applied to their wrist extensor muscles of the dominant forearm in the first two conditions. Within-subject comparisons of normalized root mean square of the wrist extensors electromyographic activity and maximal grip strength were conducted across three taping conditions. RESULTS: 31 out of 33 enlisted participants were confirmed to be ignorant about KT. No significant differences were found in the maximum grip strength (p=0.394), electromyographic activity (p=0.276), and self-perceived performance (p=0.825) between facilitatory KT, inhibitory KT, and tapeless conditions. CONCLUSIONS: Neither facilitatory nor inhibitory effects were observed between different application techniques of KT in healthy participants. Clinically, alternative method should be used for muscle activity modulation.

Kinesiology tape does not promote vertical jumping performance: A deceptive crossover trial.

BACKGROUND: Kinesiology tape (KINTAPE) is one of the most common adhesive therapeutic tapes. Apart from clinical applications, KINTAPE claims to be able to enhance functional performance by muscle activity facilitation. However, emerging evidence suggests that the isokinetic muscle strength remains similar when the placebo effect is eliminated. OBJECTIVES: In view of the weak relationship between functional performance and isokinetic muscle strength, this study investigated the true effects of KINTAPE on functional performance. DESIGN: Deceptive, randomized, and crossover trial. METHOD: Sixty four experienced volleyball players performed vertical jumping test under three taping conditions: true facilitative KINTAPE, sham KINTAPE, and no KINTAPE. Under the pretense of applying adhesive muscle sensors, KINTAPE was applied to their quadriceps and gastrocnemius in the first two conditions. Mean maximum jump height and peak jump power were averaged from three attempts. Within-subject comparisons were conducted by repeated measure ANOVA. RESULTS: Out of 64 participants, 30 of them were successfully deceived and they were ignorant about KINTAPE. No significant differences were found in both maximum jump height (η(2) = 0.001; p = 0.241) and peak jump power (η(2) = 0.001; p = 0.134) between three taping conditions. CONCLUSIONS: The results showed that KINTAPE did not facilitate muscle performance by generating higher jumping power or yielding a better jumping performance. These findings reinforce that previously reported muscle facilitatory effects or functional enhancement using KINTAPE may be attributed to placebo effects.

Intrinsic foot muscle volume in experienced runners with and without chronic plantar fasciitis.

OBJECTIVES: Plantar fasciitis, a common injury in runners, has been speculated to be associated with weakness of the intrinsic foot muscles. A recent study reported that atrophy of the intrinsic forefoot muscles might contribute to plantar fasciitis by destabilizing the medial longitudinal arch. However, intrinsic foot muscle volume difference between individuals with plantar fasciitis and healthy counterparts remains unknown. This study examined the relationship of intrinsic foot muscle volume and incidence of plantar fasciitis. DESIGN: Case-control study. METHODS: 20 experienced (≥5 years) runners were recruited. Ten of them had bilateral chronic (≥2 years) plantar fasciitis while the others were healthy characteristics-matched runners. Intrinsic muscle volumes of the participants' right foot were scanned with a 1.5T magnetic resonance system and segmented using established methods. Body-mass normalized intrinsic foot muscle volumes were compared between runners with and without chronic plantar fasciitis. RESULTS: There was significant greater rearfoot intrinsic muscle volume in healthy runners than runners with chronic plantar fasciitis (Cohen's d=1.13; p=0.023). A similar trend was also observed in the total intrinsic foot muscle volume but it did not reach a statistical significance (Cohen's d=0.92; p=0.056). Forefoot volume was similar between runners with and without plantar fasciitis. CONCLUSIONS: These results suggest that atrophy of intrinsic foot muscles may be associated with symptoms of plantar fasciitis in runners. These findings may provide useful information in rehabilitation strategies of chronic plantar fasciitis.

Effects of Surface Inclination on the Vertical Loading Rates and Landing Pattern during the First Attempt of Barefoot Running in Habitual Shod Runners.

Barefoot running has been proposed to reduce vertical loading rates, which is a risk factor of running injuries. Most of the previous studies evaluated runners on level surfaces. This study examined the effect of surface inclination on vertical loading rates and landing pattern during the first attempt of barefoot running among habitual shod runners. Twenty habitual shod runners were asked to run on treadmill at 8.0 km/h at three inclination angles (0°; +10°; -10°) with and without their usual running shoes. Vertical average rate (VALR) and instantaneous loading rate (VILR) were obtained by established methods. Landing pattern was decided using high-speed camera. VALR and VILR in shod condition were significantly higher (p < 0.001) in declined than in level or inclined treadmill running, but not in barefoot condition (p > 0.382). There was no difference (p > 0.413) in the landing pattern among all surface inclinations. Only one runner demonstrated complete transition to non-heel strike landing in all slope conditions. Reducing heel strike ratio in barefoot running did not ensure a decrease in loading rates (p > 0.15). Conversely, non-heel strike landing, regardless of footwear condition, would result in a softer landing (p < 0.011).

Kinesiology tape does not facilitate muscle performance: A deceptive controlled trial.

Kinesiology tape (KinTape) is a therapeutic tape without much understanding of its mechanism. KinTape claims to increase cutaneous stimulation, which facilitates motor unit firing, and consequently improves functional performance; however these, benefits could be due to placebo effects. This study investigated the true effects of KinTape by a deceptive, randomized, and controlled trial. Thirty healthy participants performed isokinetic testing of three taping conditions: true facilitative KinTape, sham KinTape, and no KinTape. The participants were blindfolded during the evaluation. Under the pretense of applying adhesive muscle sensors, KinTape was applied to their quadriceps in the first two conditions. Normalized peak torque, normalized total work, and time to peak torque were measured at two angular speeds (60°/s and 180°/s) and analyzed with one-way repeated measures ANOVA. Participants were successfully deceived and they were ignorant about KinTape. No significant differences were found between normalized peak torque, normalized total work, and time to peak torque at 60°/s or 180°/s (p = 0.31-0.99) between three taping conditions. The results showed that KinTape did not facilitate muscle performance in generating higher peak torque, yielding a greater total work, or inducing an earlier onset of peak torque. These findings suggest that previously reported muscle facilitatory effects using KinTape may be attributed to placebo effects.

Motion control shoe affects temporal activity of quadriceps in runners.

OBJECTIVE: Delay onset of the vastus medialis obliquus (VMO) has often been reported to happen in people with patellofemoral pain (PFP). Previous studies revealed that a motion control shoe could check rearfoot pronation in overpronators. Literature suggested that movements of the lower leg could affect patellar tracking; thus motion control shoe may help prevent PFP by controlling excessive foot movements. This study aimed to compare the vasti muscle activities in people with excessive foot pronation when running with different footwear. METHODS: Twenty female subjects with rearfoot pronation >6 degrees were tested by running for 10 km on a treadmill on two separate days. During each test, subjects either wore a motion-control running shoe or a neutral running shoe. EMG activities of their right VMO and vastus lateralis (VL) were recorded. Their EMG onset timing and median frequency (MF) were compared between the two shoe conditions. RESULTS: A more significant delay in VMO onset of the running duty cycle was observed in the neutral shoe condition than in the motion control shoe (p<0.001). In the neutral shoe condition, the delay in VMO increased with running mileage (Pearson correlation = 0.948), whereas no such pattern was observed in the motion control shoe. A significant drop in MF of the quadriceps after the 10 km run in both shoe conditions was observed (p ranged from <0.001 to 0.008), and there was a larger drop in VMO MF when running with the neutral shoe. CONCLUSIONS: The findings suggest that the motion control shoe may facilitate a stable temporal activation of VMO during running.