The purpose of this study was to compare lower extremity joint angular position and muscle activity during elliptical exercise using different foot positions and also during exercise on a lateral elliptical trainer. Sixteen men exercised on a lateral elliptical and on a standard elliptical trainer using straight foot position, increased toe-out angle, and a wide step. Motion capture and electromyography systems were used to obtain 3D lower extremity joint kinematics and muscle activity, respectively. The lateral trainer produced greater sagittal and frontal plane knee range of motion (ROM), greater peak knee flexion and extension, and higher vastus medialis activation compared with other conditions (P < .05). Toe-out and wide step produced the greatest and smallest peak knee adduction angles, respectively (P < .05). The lateral trainer produced greater sagittal and frontal plane hip ROM and greater peak hip extension and flexion compared with all other conditions (P < .05). Toe-out angle produced the largest peak hip external rotation angle and lowest gluteus muscle activation (P < .05). Findings from this study indicate that standard elliptical exercise with wide step may place the knee joint in a desirable frontal plane angular position to reduce medial knee loads, and that lateral elliptical exercise could help improve quadriceps strength but could also lead to larger knee contact forces.
Max R. Paquette, Audrey Zucker-Levin, Paul DeVita, Joseph Hoekstra and David Pearsall
Stephanie Chester, Audrey Zucker-Levin, Daniel A. Melcher, Shelby A. Peel, Richard J. Bloomer and Max R. Paquette
The purpose of this study was to compare knee and hip joint kinematics previously associated with anterior knee pain and metabolic cost among conditions including treadmill running (TR), standard elliptical (SE), and lateral elliptical (LE) in healthy runners. Joint kinematics and metabolic parameters of 16 runners were collected during all 3 modalities using motion capture and a metabolic system, respectively. Sagittal knee range of motion (ROM) was greater in LE (P < .001) and SE (P < .001) compared with TR. Frontal and transverse plane hip ROM were greater in LE compared with SE (P < .001) and TR (P < .001). Contralateral pelvic drop ROM was smaller in SE compared with TR (P = .002) and LE (P = .005). Similar oxygen consumption was found during LE and TR (P = .39), but LE (P < .001) and TR (P < .001) required greater oxygen consumption than SE. Although LE yields similar metabolic cost to TR and produces hip kinematics that may help strengthen hip abductors, greater knee flexion and abduction during LE may increase symptoms in runners with anterior knee pain. The findings suggest that research on the implications of elliptical exercise for injured runners is needed.
Margaret K.Y. Mak, Oron Levin, Joseph Mizrahi and Christina W.Y. Hui-Chan
Calculation of joint torques during the rising phase of sit-to-stand motion is in most cases indeterminate, due to the unknown thighs/chair reaction forces in addition to the other sources of uncertainties such as joint positioning and anthropometric data. In the present study we tested the reliability of computation of the joint torques from a five-segment model; we used force plate data of thighs/chair and feet/ground reaction forces, in addition to kinematic measurements. While solving for joint torques before and after seat-off, differences between model solutions and measured data were calculated and minimized using an iterative algorithm for the reestimation of joint positioning and anthropometric properties. The above method was demonstrated for a group of six normal elderly persons.
Renato Rodano and Roberto Squadrone
Stability and consistency is a critical aspect in joint kinetic measurements. By applying a statistical technique, called sequential estimation procedure, the aim of this work was to determine the minimum number of trials required to obtain a stable mean for peak hip, knee, and ankle moments and powers during vertical jump. Nine competitive track and field sprinters (21.7 ± 3.5 yrs, 177.6 ± 4.3 cm, 70.8 ± 3.6 kg) performed 5 series of 5 double-legged maximum-height countermovement vertical jumps. From force platform and kinematic data, moment and power output were calculated for hip, knee, and ankle joints. The sequential estimation procedure applied to these data revealed that at least a 12-trial protocol is needed to establish a true measure for all the selected parameters. The mean number of trials for each variable was greater than 8 and less than 13. When hip moments were excluded from the analysis, a 10-trial protocol could be sufficient to reach a stable mean. In conclusion. the results of this study gave statistical evidence for the need to adopt multiple-trial protocols in order to obtain a stable mean for joint kinetic data.
Yaara Nadiv, Ricki Vachbroit, Amit Gefen, David Elad, Uri Zaretsky, Dani Moran, Pinchas Halpern and Anat Ratnovsky
The respiratory muscles may fatigue during prolonged exercises and thereby become a factor that limits extreme physical activity. The aim of the current study was to determine whether respiratory muscle fatigue imposes a limitation on extreme physical activity of well-trained young men. Electromyography (EMG) signals of respiratory (external intercostal and sternomastoid) and calf muscles (gastrocnemius) were measured (N = 8) during 1 hr of treadmill marching at a speed of 8 km/hr with and without a 15 kg backpack. The root mean square (RMS) and the mean power frequency of the EMG signals were evaluated for calculating fatigue indices. The EMG RMS revealed that the respiratory and calf muscles did not fatigue during the marching without a backpack load. The study did show, however, a significant rise in the EMG values when a backpack was carried with respect to the no-load condition (p < .05), which suggests that respiratory muscles should be trained in military recruits who are required to carry loaded backpacks while marching.
George Vagenas and Blaine Hoshizaki
This study investigated the phenomenon of lower extremity functional asymmetries in a group of competitive male distance runners (N = 29). Bilateral measurements were taken to assess selected variables of the talocalcaneal flexibility (goniometry) and of the isokinetic knee strength (Cybex II). Data analysis revealed significant asymmetries for both lower extremity functional parameters. The subjects were symmetric in the total range of motion of the subtalar joint and inversely asymmetric in the range of motion of calcaneal eversion and calcaneal inversion. The laterality patterns of functional asymmetries were found to be consistent and independent of the conventional upper and lower extremity lateral preferences. It was theorized that asymmetries in the lower extremities are characterized by joint-specific trends of bilateralism.
Gabriel Andrade Paz, Jason DeFreitas, Marianna de Freitas Maia, Jurandir Silva, Vicente Lima and Humberto Miranda
Excessive valgus and varus force which affected the knee joint during dynamic tasks has been often associated to lower extremity injuries. Strategies to increase the resistance against these asymmetries (eg, the use of a physioball between the knees or elastic bands around the knees) are often applied in rehabilitation and conditioning programs.
The purpose of this study was to investigate the effect of performing leg press (LP) 45° using a physioball and elastic band over multiple sets with submaximal loads on electromyographic (EMG) amplitude and fatigue indices.
18 trained females volunteered (age: 24.4 ± 2.1 y; height: 168.1 ± 4 cm; body mass: 65.1 ± 4.4 kg) participated in this study. The 10 repetition maximum (RM) loads were determined for the LP. Then, 3 experimental protocols were followed in a randomized crossover design over 3 nonconsecutive days: control protocol—the participants performed 4 LP sets; physioball between knees—4 LP sets were performed with the physioball between the knees; elastic band—4 LP sets were performed with the elastic band involving the knees. Ten repetitions were performed during each set with 70% of 10-RM loads; EMG spectral indices (CRMS and Cf5) was collected from the biceps femoris (BF), vastus lateralis (VL), vastus medialis obliquus (VMO), and rectus femoris (RF) muscles.
Higher levels of CRMS and Cf5 were noted for RF, VL, and VM muscles using the physioball and elastic band when compared with control protocol, respectively. CRMS index of BF muscle was significantly higher using physioball and elastic band protocol versus control condition, respectively.
Therefore, both physioball and elastic band can be adopted during LP with the goal to reduce excessive varus and valgus forces, respectively, even performing consecutive sets with submaximal loads. Furthermore, this may be an interesting alternative to increasing quadriceps activation and improving the knee joint stabilization.
Mati Pääsuke, Jaan Ereline, Helena Gapeyeva, Kadri Joost, Karin Mõttus and Pille Taba
The lower extremity performance in elderly female patients with mild to moderate Parkinson’s disease (PD; n = 12) and controls (n = 16) was compared. Isometric dynamometry and force-plate measurements were used. PD patients had lower (p < .05) bilateral (BL) maximal isometric leg-extension force (MF), BL isometric MF relative to body mass, and maximal rate of isometric force development than control participants. BL strength deficit was greater (p < .05) in PD patients than in controls. A significantly longer chair-rise time and lower maximal rate of vertical-ground-reaction-force development while rising from a chair was found in PD patients than in controls. These findings suggest that elderly women with PD have lowered voluntary isometric force-generation capacity of the leg-extensor muscles. Reduced BL leg-extension strength might contribute to the difficulty of individuals with PD to rise from a chair.
Marcos de Noronha, Eleisha K. Lay, Madelyn R. Mcphee, George Mnatzaganian and Guilherme S. Nunes
Context: Ankle sprains are common injuries in sports, but it is unclear whether they are more likely to occur in a specific period of a sporting game. Objective: To systematically review the literature investigating when in a match ankle sprains most likely occurred. Evidence Acquisition: The databases CINAHL, EMBASE, MEDLINE, and SPORTDiscus were searched up to August 2016, with no restriction of date or language. The search targeted studies that presented data on the time of occurrence of ankle sprains during sports matches. Data from included studies were analyzed as a percentage of ankle sprain occurrence by halftime and by quarters. Meta-analyses were run using a random effects model. The quality assessment tool for quantitative studies was used to assess the article’s quality. Evidence Synthesis: The searches identified 1142 studies, and 8 were included in this review. A total of 500 ankle sprains were reported during follow-up time, which ranged from 1 to 15 years, in 5 different sports (soccer, rugby, futsal, American football, and Gaelic football). The meta-analyses, including all 8 studies, showed that the proportion of ankle sprains during the first half (0.44; 95% confidence interval [CI], 0.38–0.50) was smaller than the second half (0.56; 95% CI, 0.50–0.62). For the analyses by quarters, the proportion of ankle sprains in the first quarter (0.14; 95% CI, 0.09–0.19) was considerably smaller than the second (0.28; 95% CI, 0.24–0.32), third (0.25; 95% CI, 0.17–0.34), and fourth (0.29; 95% CI, 0.22–0.36) quarters. Conclusion: The results of this review indicate that ankle sprains are more likely to occur later in the game during the second half or during the latter minutes of the first half.
Montassar Tabben, Daniele Conte, Monoem Haddad and Karim Chamari
, Kizami-Zuki, Gyaku-zuki, Oi-zuki, etc). Lower limb actions represent any kicking techniques (eg, Mae-geri, Uko-geri , Mawashi-geri , etc). Throwing is defined as any grappling techniques that involve off-balancing an opponent, and throwing him/her to the ground regardless of the fact that it leads to punch