Do People with Mental Impairment Present Jumping Gain during Drop Jumps from Various Dropping Heights

IntroductionStretch-shortening cycle (SSC) is a complex movement where the muscle tendon unit (MTU) is initially stretched and afterwards is contracted concentrically. SSC causes an initial storage of elastic energy on the elastic tissue which is recoiled during the concentric phase causing thus an enhancement in the performance (Bosco, Komi, & Ito, 1981; Bosco, Tihanyi, Komi, Fekele, & Apor, 1982). SSC is characteristic for action like the drop jump (DJ) which is a very common task and training modality in various organized sport activities. Relevant studies (Komi & Bosco, 1978) have showed that jumping height of a DJ is in many cases higher than a squat jump (SJ). This difference is called jump gain (JG) and is depended on several factors sush as MTU stiffness, preactivation, agonist activity and stretch reflex (Taube, Leukel, & Gollhofer, 2012). Additionally, among these factors, JG depends on the dropping height (DH). It has been found that that up to a certain DH, jumping height is increased, then it is stabilized and from a certain DH upwards it is gradually decreased (Komi & Bosco, 1978; Voight, Simonsen, Dyhre-Poulsent, & Klausen, 1995) due to various peripheral and central inhibitory factors (Leukel, Taube, Gruber, Hodapp, & Gollhofer, 2008). Moreover, JG is also depended on performance level, gender and age (Komi & Bosco, 1978; Bosco, & Komi, 1980; Horita, Komi, Hamalainen, & Avela, 2003). Specifically, it has been reported that women achieve JG in lower DH than men (Komi & Bosco, 1978; Bosco & Komi, 1980), while athletes achieved JG in higher DH than untrained persons.Aditionally children do not present any JG from various DJ (Bassa, Patikas, Panagiotidou, Papadopoulou, Pylianidis, & Kotzamanidis, 2012; Lazardis, Bassa, Patikas, Hatzikotoulas, Lazaridis, & Kotzamanidis, 2013). The research related with people with mental impairment (MI) is not extensive. Generally speaking, MI have a deficit compared to typical population for fitness parameters such as strength and motor skill (LeClair, Pollock, & Elliott, 1993; Vuijk, Hartman, Scherder, & Visscher, 2010). This has been attributed to a failure of central drive (Haier, Jungb, Yeoc, Heada, & Alkired, 2004; Yu, Li, Liu, Qin, Li, Shu, N., et al. 2008) and to environmental parameters such as inactivity (Horvat & Franklin, 2001). The majority of studies regarding jumping performance are related with horizontal jumping (Skowronski, Horvat, Nocera, Roswal, & Croce, 2009). Nevertheless, few studies have addressed vertical jumping in MI (Hassani, Kotzamanidou, Fotiadou, Patikas, Evagelinou, & Sakadami, 2013; Hassani, Kotzamanidou, Tsimaras, Lazaridis, Kotzamanidis, & Patikas, 2014). These studies found that the jumping deficit in MI could be attributed to parameters such as lower power, poorer coordination, lower agonist activity, lower stiffness and to a higher antagonist activity.According to our best knowledge, there are no studies which investigated the possible JG from various DH in MI. This fact is very important considering that plyometric training is gradually involved in MI (Harries, Lubans, & Callister, 2012; Johnson, Salzberg, & Stevenson, 2011). Due to the above, the selection of DH in plyometric exercises for PMI seems to be a crucial question. Thus, the purpose of this study was to investigate the JG after various DH in MI.MethodParticipantsEleven (n = 11) adult males with MI participated voluntarily in this study (Height: 173.7 ± 14.4 cm, Body mass: 73.7 ± 19.3 kg, Age: 25.9 ± 6.5 yrs). The intelligence quotient in the MI group was 54.6 ± 11.2, as estimated by Wisk III test.No neurological deficit and injuries history that could influence lower extremity performance was reported by the participants. Before testing, the participants were familiarized with the laboratory environment. They read and signed a written informed consent statement. …