Débora Cantergi

Muscle strategies for leg extensions on a "Reformer" apparatus.

Considering the kinematics of leg extensions performed on a Reformer apparatus, one would expect high activation of hip and knee extensor muscle groups. However, because of the bi-articular nature of some lower limb muscles, and the possibility to vary the direction of force application on the Reformer bar, muscles can be coordinated theoretically in a variety of ways and still achieve the desired outcome. Hence, the aim of this study was to determine the knee and hip moments during leg extensions performed on the Reformer apparatus and to estimate the forces in individual muscles crossing these joints using static optimization. Fifteen subjects performed leg extensions exercises on the Reformer apparatus using an individually chosen resistance. To our big surprise, we found that subjects performed the exercise using two conceptually different strategies (i) the first group used simultaneous hip and knee extension moments, (ii) while the second group used simultaneous hip flexion and knee extension moments to perform the exercise. These different strategies were achieved by changing the direction of the resultant force applied by the subjects feet on the Reformer bar. While leg extensions on the Reformer apparatus have been thought to strengthen the hip and knee extensors muscles, our results demonstrate that patients can perform the exercise in a different and unexpected way. In order to control the hip and knee moments and achieve the desired outcome of the exercise, the direction of force application on the Reformer bar must be controlled carefully.

EMG Analysis of a Pilates Exercise

The Pilates method was originally developed by Joseph Pilates in Germany during the First World War and introduced in the United States in 1923 (Latey, 2001; Muscolino & Cipriani, 2004; Rydeard et al., 2006). The method assembles movements from gymnastics, martial arts, yoga and dance with philosophic ideas (Self et al., 1996; Latey, 2001; Rydeard et al., 2006). After the 1980’s, new elements were incorporated aiming to improve both physical conditioning and rehabilitation programs. When considering physical conditioning increases in joint flexibility, muscle strength, balance and whole body conditioning were observed in Pilates’ practitioners (Bertolla F, 2007; Jago et al., 2006; Segal et al., 2004). For rehabilitation, Pilates exercises have been used for joint function restoration, lumbar-pelvic stabilization, fibromyalgia control and low back pain treatment (Blum, 2002; Kolyniak et al., 2004; Donzelli et al., 2006). In order to achieve the program goals, the health professionals can choose between mat or apparatus exercises. The apparatus, such as the reformer or the Cadillac, were designed specifically for the Pilates method. These apparatus uses springs in order to generate external load for the musculoskeletal structure. In general, each spring presents a different elastic constant and has more than one attachment possibility in the different apparatus, reflecting in the external load (Self et al., 1996; Rydeard et al., 2006). Regardless of the objectives, it is recommended that the training program uses exercises with progressive external load, according to each individual’s needs. However, what have been observed is that the determination of external load in Pilates’ exercises is based on subjective information, such as changing a less resistance for a higher resistance spring, without realizing how high is the difference in each situation. When this is follower, intensity is only determined based on patient’s feedback and the instructor’s experience (Blum, 2002), what may affect negatively the Pilates training program success. Attentive to this situation, the Mechanics of Movement Investigation Group (BIOMEC Grupo de Investigacao em Mecânica do Movimento) has been using biomechanical analysis of human movement, in order to identify the resistance moments curve shape in a quantitative analysis of Pilates exercises (Silva et al., 2009; Loss et al., 2010; Melo et al., 2011). Thus, besides using load cells for measuring spring’s strength (Self et al., 1996), resistance moment may be estimated in different subjects positioning and spring setups (Silva et al., 2009).

Evaluating the Electromyographical Signal During Symmetrical Load Lifting

Muscular problems account for almost half the cases of work absence, with the back being the region most involved (Kumar, 2011). Bending the trunk forward while performing domestic work or sports related activities is the cause of most back injuries (Fathallah et al., 1998). Small degrees of flexion of the trunk can be considered a medium to high risk factor of injury, mainly when the angle of the forward inclination is greater than 15 degrees and is combined with lifting activities. As the task of lifting objects from the ground exposes spinal structures to muscular-skeletal overload it has been consistently investigated (Simon, 1997). In addition, epidemiological research associates lifting to the risk of developing lumbar back pain (Ferguson & Marras, 1997; Dolan & Adams, 1998; Jager & Luttmann, 1999; Nachemson, 1999; Wilke et al., 1999; Burdorf, 2000; Kingma et al., 2001; Wilke et al., 2001; Ferguson et al., 2004). In the early 20th century, the scientific community was already studying back injuries, in particular low back pain (Ghormley, 1933), and its relation with the loads that affect the spine. Due to the invasive nature of measuring these internal loads, models employing indirect means of estimating the loads that act on the lumbar region of the spine during lifting activities began to appear in the 1940s (Wilke et al., 2001). The models found in the literature continue to be primarily concerned with the forces between the muscles, joints and ligaments in only one cross section of the lumbar region (Strait et al., 1947; Cheng, 1998; Gagnon, 2001). While considering the spine as a single rigid structure, these simplified models attempt to provide estimates of what occurs in the spine in situations such as lifting a weight. However, these models are far from representative of the functional anatomical reality of the spine, which consists of several articulated segments and a complex muscle anatomy. The growing interest in producing a more realistic model of the trunk and, consequently, the spine, may have inspired some anthropometric studies (De Leva, 1996; Erdmann, 1997; Zatsiorsky, 2002) to divide the trunk into two or more connected segments. Some models that split the spine into more than one segment are conceived using biomechanical techniques, such as the link segment model (LSM), surface electromyography (EMG) and inverse dynamics (Lariviere, 1999; Marras, 1997; La Torre, 2005). The EMG of the trunk muscles has been used as input for biomechanical models that attempt to indirectly estimate the forces acting on the spine (Granata, 1995; Arjmand, 2006).

Electrical Activity of Powerhouse Muscles During the Teaser Exercise of Pilates Using Different Types of Apparatus

We compared the electrical activity of certain powerhouse muscles—External Oblique, Multifidus, Adductor Longus, and Gluteus Medius—during the teaser exercise of the Pilates Method, performed on various types of apparatus—the Mat, Reformer, and Wall Unit. Fifteen female practitioners of the Classic Pilates Method (32.6 ± 7.7 years old; 21.9 ± 1.9 body mass index) performed the teaser in each situation while electromyographic (EMG) and kinematic data were collected. Root mean square values of the flexion phase were compared. All muscles showed higher EMG activity in Reformer compared with Wall Unit, and Multifidus, Adductor Longus, and Gluteus Medius showed higher EMG activity in Mat compared with Wall Unit. No difference was found between Reformer and Mat.

La influencia de kihapsobre el impacto de las patadas Dolio-Chaguien taekwondo

O kihape uma tecnica utilizada em diversas artes marciais orientais. Ele e um grito utilizado pelo praticante com a expectativa de aumentar a forca do golpe. Entretanto, o real efeito do uso do kihape desconhecido. Assim, esse estudo tem por objetivo comparar o pico de aceleracao do chute Dolio-chaguido taekwondo realizado com e sem o uso de kihap. Vinte e dois praticantes experientes de taekwondo realizaram 30 chutes contra um saco de pancadas, alternando em ordem randomizada com e sem o uso do kihap, enquanto a aceleracao do saco de pancadas foi mensurada. Um teste-tfoi utilizado para comparar a diferenca entre a aceleracao media em ambas as condicoes. Valores mais altos foram encontrados com o uso do kihap(7,8 ± 2,8 g) do que sem o uso do kihap(7,1 ± 2,4 g), p< 0,01, r= 0,57. Os resultados indicam que o kihapaumenta o impacto do chute.

The influence of kihap on the impact of Dolio-chagui kicks in taekwondo

O kihape uma tecnica utilizada em diversas artes marciais orientais. Ele e um grito utilizado pelo praticante com a expectativa de aumentar a forca do golpe. Entretanto, o real efeito do uso do kihape desconhecido. Assim, esse estudo tem por objetivo comparar o pico de aceleracao do chute Dolio-chaguido taekwondo realizado com e sem o uso de kihap. Vinte e dois praticantes experientes de taekwondo realizaram 30 chutes contra um saco de pancadas, alternando em ordem randomizada com e sem o uso do kihap, enquanto a aceleracao do saco de pancadas foi mensurada. Um teste-tfoi utilizado para comparar a diferenca entre a aceleracao media em ambas as condicoes. Valores mais altos foram encontrados com o uso do kihap(7,8 ± 2,8 g) do que sem o uso do kihap(7,1 ± 2,4 g), p< 0,01, r= 0,57. Os resultados indicam que o kihapaumenta o impacto do chute.

A influência do kihapsobre o impacto de chutes Dolio-Chaguino taekwondo

O kihape uma tecnica utilizada em diversas artes marciais orientais. Ele e um grito utilizado pelo praticante com a expectativa de aumentar a forca do golpe. Entretanto, o real efeito do uso do kihape desconhecido. Assim, esse estudo tem por objetivo comparar o pico de aceleracao do chute Dolio-chaguido taekwondo realizado com e sem o uso de kihap. Vinte e dois praticantes experientes de taekwondo realizaram 30 chutes contra um saco de pancadas, alternando em ordem randomizada com e sem o uso do kihap, enquanto a aceleracao do saco de pancadas foi mensurada. Um teste-tfoi utilizado para comparar a diferenca entre a aceleracao media em ambas as condicoes. Valores mais altos foram encontrados com o uso do kihap(7,8 ± 2,8 g) do que sem o uso do kihap(7,1 ± 2,4 g), p< 0,01, r= 0,57. Os resultados indicam que o kihapaumenta o impacto do chute.