Many activities necessitate a high degree of static joint range of motion (ROM) for an extended duration. The objective of this study was to examine whether ROM could be improved with a short duration and volume of static stretching within a warm-up, without negatively impacting performance. Ten male recreationally active participants completed 2 separate protocols to examine changes in ROM and performance, respectively, with different warm-ups. The warm-up conditions for the ROM protocol were static stretching (SS), consisting of 6 repetitions of 6 s stretches; 10 min of running prior to the SS (AS); and 5 min of running before and after the SS (ASA). The performance protocol included a control condition of 10 min of running. Measures for the ROM protocol included hip flexion ROM, passive leg extensor tension, and hamstring electromyographic (EMG) activity at pre-warm-up, and at 1, 10, 20, and 30 min post-warm-up. Performance measures included countermovement jump (CMJ) height, reaction time (RT), movement time (MT), and balance at pre-warm-up and at 1 and 10 min post-warm-up. The ASA produced greater ROM overall than the SS and AS conditions (p < 0.0001), persisting for 30 min. There were no significant alterations in passive muscle tension or EMG. For the performance protocol, there were no main effects for condition, but there was a main effect for time, with CMJ height being greater at 1 and 10 min post-warm-up (p = 0.0004). Balance ratios and MT improved at 10 min post-warm-up (p < 0.0001). Results indicate that the ASA method can provide ROM improvements for 30 min with either facilitation or no impairment in performance. This may be especially important for athletes who substitute later into a game with minimal time for a full warm-up.
Massage for the purpose of health dates back to early civilization and more recently has been used in the management and prevention of sport injuries. Massage has also been used as part of a warm-up to help increase acute flexibility. However, the physiological benefits and mechanisms of massage are not well known. The purpose of the present study was to investigate the effectiveness of 3 massage conditions on hip flexion range of motion (ROM). This experimentation involved a novel massage technique, which focused the massage on the musculotendinous junction for a short duration. Ten recreationally active women ranging from 21 to 36 years in age participated in this study. Participants were subjected to 3 massage conditions (no massage, 10-second massage, and 30-second massage) in a random order on separate days. Hip flexion angle, passive leg tension, and electromyography (EMG) were measured thrice before and within 10 seconds after the intervention. A main effect for conditions was found with the 30-second massage providing a 7.2% increase in hip flexion ROM that was significantly greater than the control condition (p < 0.05). Significant interactions occurred with an increased ROM (p < 0.05) from pre to posttests of 5.9 and 7.2% for the 10- and 30-second massage conditions, respectively. There were no significant differences in passive tension or EMG for any conditions or time. With a significant increase in hip angle and no associated increase in passive tension or EMG, there is a suggestion that 10 and 30 seconds of musculotendinous massage induces greater ROM through a modified stretch perception, increased stretch tolerance, or increased compliance of the hamstrings. Musculotendinous massage may be used as an alternative or a complement to static stretching for increasing ROM.
Soil water content is an important factor influencing NH3 volatilization from N fertilizers. Information on the relationship between water evaporation and NH3 volatilization from urea (U) or urea‐ammonium nitrate (UAN) solutions, and on the kinetics of both processes is lacking. We examined NH3 volatilization from surface‐applied solutions of U and UAN in samples of St. Bernard (loamy, mixed, nonacid, frigid Typic Hapludoll) and Ste. Sophie (sandy, mixed, nonacid, frigid Typic Haplorthod) soils exposed to water potentials ranging from < −1.5 to −0.01 MPa. An air‐train system was used. Ammonia volatilization increased as soil water content increased. Volatilization differences between moist (> −0.038 MPa) and air‐dry (< −1.5 MPa) samples were reduced as the clay content of the soil increased. However, the effect of clay content on NH3 volatilization became more pronounced as soil approached air dryness. Water evaporation was consistent with first‐order kinetics, whereas NH3 volatilzation followed two first‐order kinetics. The initial rate constants (k1) for NH3 volatilization (0.338–0.348 d−1) from U solution were consistently higher than those for water evaporation (0.099–0.104 d−1) at −0.01 MPa water potential and 70% relative humidity. Differences could be attributed to different energy requirements. Ammonia volatilization vs. water evaporation followed a logarithmic relationship.
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