Sex variation in patellar tendon kinetics during running

Purpose. The aim of the current investigation was to determine whether female recreational runners exhibit distinct patellar tendon loading patterns in relation to their male counterparts. Methods. Twelve male (age 26.55 ± 4.11 years, height 1.78 ± 0.11 m, mass 77.11 ± 5.06 kg) and twelve female (age 26.67 ± 5.34 years, height 1.67 ± 0.12 m, mass 63.28 ± 9.75 kg) runners ran over a force platform at 4.0 m · s –1. Lower limb kinematics were collected using an eight-camera optoelectric motion capture system which operated at 250 Hz. Patellar tendon loads were examined using a predictive algorithm. Sex differences in limb, knee and ankle joint stiffness were examined statistically using independent samples t tests. Results. The results indicate that patellar tendon force (male = 6.49 ± 2.28, female = 7.03 ± 1.35) and patelllar tendon loading rate (male = 92.41 ± 32.51, female = 111.05 ± 48.58) were significantly higher in female runners. Conclusions. Excessive tendon loading in female runners indicates that female runners may be at increased risk of patellar tendon pathologies

Multi-segment foot kinematics and plantar fascia strain during treadmill and overground running

Although physiologically beneficial, running is known to be associated with a high incidence of chronic injuries. Excessive coronal and transverse plane motions of the foot segments and strain experienced by the plantar fascia are linked to the development of a number of chronic injuries. This study examined differences in multi-segment foot kinematics and plantar fascia strain during treadmill and overground running. Twelve male recreational runners ran at 4.0 m.s-1 in both treadmill and overground conditions. Multi-segment foot kinematics and plantar fascia strain were measured using an eight-camera motion analysis system and contrasted using paired samples t-tests. The results showed that plantar fascia strain was significantly greater in the overground condition (8.23 ± 2.77) compared to the treadmill (5.53 ± 2.25). Given the proposed relationship between excessive plantar fascia strain and the etiology of injury, overground running may be associated with a higher incidence of injury although further work is necessary before causation can be confirmed

The effects of shoe temperature on the kinetics and kinematics of running

The aim of the current investigation was to examine the effects of cooled footwear on the kinetics and kinematics of running in comparison to footwear at normal temperature. Twelve participants ran at 4.0 m/s ± 5% in both cooled and normal temperature footwear conditions over a force platform. Two identical footwear were worn, one of which was cooled for 30 min. Lower extremity kinematics were obtained using a motion capture system and tibial accelerations were measured using a triaxial accelerometer. Differences between cooled and normal footwear temperatures were contrasted using paired samples t-tests. The results showed that midsole temperature (cooled = 4.21 °C and normal = 23.25 °C) and maximal midsole deformation during stance (cooled = 12.85 mm and normal = 14.52 mm) were significantly reduced in the cooled footwear. In addition, instantaneous loading rate (cooled = 186.21 B.W/s and normal = 167.08 B W/s), peak tibial acceleration (cooled = 12.75 g and normal = 10.70 g) and tibial acceleration slope (cooled = 478.69 g/s and normal = 327.48 g/s) were significantly greater in the cooled footwear. Finally, peak eversion (cooled = −10.57 ° and normal = −7.83°) and tibial internal rotation (cooled = 10.67 ° and normal = 7.77°) were also shown to be significantly larger in the cooled footwear condition. This study indicates that running in cooled footwear may place runners at increased risk from the biomechanical parameters linked to the aetiology of injuries

Effects of new military footwear on knee loading during running

Military recruits are known to be susceptible to chronic injuries. The knee is the most common injury site and patellofemoral pain has been demonstrated as the leading mechanism for medical military discharge. Military boots have been cited as a key mechanism responsible for the high incidence of chronic injuries. The British Army has therefore introduced two new footwears – a cross-trainer and running shoe to reduce the incidence of chronic injuries. The aim of this study was to compare knee joint kinetics of the cross-trainer and running shoe in relation to conventional military boots. Twelve male participants ran at 4.0 m s−1 in each footwear condition. Knee joint kinetics was obtained and contrasted using repeated-measures ANOVAs. The results showed that patellofemoral load was significantly greater in the military boots. However, peak knee abduction moment was significantly greater in the running shoes. On the basis of the findings from this study, it is recommended that recruits who are susceptible to injuries mediated through excessive knee loads select the cross-trainer for their running activities

From Latin Americans to Latinos: Spanish-language television in the United States and its audiences

This paper will outline the diversity amongst the peoples of Spanish-speaking origin in the US, and examine how, even in spite of their various efforts to forge cultural identities on their own terms, the institutions of government, media and marketing have ascribed to these various peoples a common cultural identity for them to assume within the mainstream. On the other hand, by reference to the Spanish-language television industry in particular, the paper also offers a case study in how institutions are having to adapt to the pressures they face in an era of increased cultural diversity within the nation-state and movement of peoples across its borders.Este artigo irá delinear a diversidade existente entre os povos de origem e língua espanhola nos Estados Unidos e examinar como, apesar dos vários esforços dos mesmos em forjar identidades culturais próprias, as instituições governamentais, a mídia e o marketing atribuíram a esses vários povos uma identidade cultural comum dentro de sua cultura dominante. Por outro lado, em relação à indústria televisiva em língua espanhola em particular, o artigo oferece um estudo de caso sobre como as instituições estão tendo que se adaptar às pressões que enfrentam numa era de crescente diversidade cultural dentro dos EUA e do movimento de povos através de suas fronteiras

Sex differences in limb and joint stiffnes in recreational runners

Purpose. Female runners are known to be at greater risk from chronic running injuries than age-matched males, although the exact mechanisms are often poorly understood. The aim of the current investigation was to determine if female recreational runners exhibit distinct limb and joint stiffness characteristics in relation to their male counterparts. Methods. Fourteen male and fourteen female runners ran over a force platform at 4.0 m · s–1. Lower limb kinematics were collected using an eight-camera optoelectric motion capture system operating at 250 Hz. Measures of limb and joint stiffness were calculated as a function of limb length and joint moments divided by the extent of limb and joint excursion. All stiffness and joint moment parameters were normalized to body mass. Sex differences in normalized limb and knee and ankle joint stiffness were examined statistically using independent samples t tests. Results. The results indicate that normalized limb (male = 0.18 ± 0.07, female = 0.37 ± 0.10 kN · kg · m–1) and knee stiffness (male = 5.59 ± 2.02, female = 7.34 ± 1.78 Nm · kg · rad–1) were significantly greater in female runners. Conclusions. On the basis that normalized knee and limb stiffness were shown to be significantly greater in female runners, the findings from the current investigation may provide further insight into the aetiology of the distinct injury patterns observed between sexes

The Effects of Barefoot and Shod Running on Limb and Joint Stiffness Characteristics in Recreational Runners.

The authors aimed to determine the effects of barefoot (BF) and several commercially available barefoot-inspired (BFIS) footwear models on limb and joint stiffness characteristics compared with conventional footwear (CF). Fifteen male participants ran over a force platform at 4.0 m.s-1, in BF, BFIS, and CF conditions. Measures of limb and joint stiffness were calculated for each footwear. The results indicate that limb and knee stiffness were greater in BF and minimalist BFIS than in CF. CF and more structured BFIS were associated with a greater ankle stiffness compared with BF and minimalist BFIS. These findings serve to provide further insight into the susceptibility of runners to different injury mechanisms as a function of footwear

Agreement Between the Stages Cycling and SRM Powermeter Systems during Field-Based Off-Road Climbing.

The aim of this study was to determine the agreement between two portable cycling powermeters for use doing field based mountain biking. A single participant performed 15 timed ascents of an off-road climbs. The participants bicycle was instrumented with Stages Cycling and SRM powermeters. Mean and peak power output and cadence were recorded at 1 s intervals by both systems. Significant differences were determined using paired t-tests, whilst agreement was determined using 95% ratio limits of agreement (LoA). Significant differences were found between the two systems for mean power output (p<.001), with the Stages powermeter under reporting power by 8 % compared to the SRM. LoA for mean power output were 0.92 ×÷ 1.02 (95% LoA = 0.90 – 0.93). Peak power output was also significantly lower with the Stages powermeter (p=.02) by 5 % when compared to the SRM powermeter. LoA for peak power output were 0.94 ×÷ 1.09 (95% limits of agreement = 0.87 – 1.03). Significant differences were found for mean cadence between the two powermeters (p=.009), with LoA being 0.99 ×÷ 1.01 (95% limits of agreement = 0.99 – 1.00). This study found that though the Stages Cycling powermeter provided a reliable means of recording power output and cadence, the system significantly underestimated mean and peak power output when compared with the SRM system. This may in part be due to differences in strain gauge configuration and the subsequent algorithms used in the calculation of power output and the potential influence of bilateral imbalances within the muscles may have on these calculations