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Max Pietrzak and Niels B.J. Vollaard

Australian Football League players with HSI resulted in significantly faster return to play. Human in-vivo hamstring stretching studies in noninjured subjects strongly supports stretch tolerance as a primary mechanism responsible for lasting increases in hamstring extensibility utilizing intervention

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Ulrike H. Mitchell, J. William Myrer, J. Ty Hopkins, Iain Hunter, J. Brent Feland and Sterling C. Hilton

Background and Purpose:

Proprioceptive neuromuscular facilitation (PNF) stretches are widely used in athletics and rehabilitation. Although it has been shown that they produce better range-of-motion (ROM) increases than the slow or static stretch, the mechanisms responsible remain an enigma. This study was conducted to determine whether the previously proposed neurophysiological mechanisms of reciprocal inhibition and autogenic inhibition are responsible for the success of PNF stretches. In addition, the authors assessed the existence of the phenomenon of successive induction because it is used to strengthen reciprocal inhibition.

Methods:

Eighteen subjects 17–44 y performed the PNF stretches contract-relax (CR) and contract-relax, agonist contract (CRAC). EMG data were collected from the medial hamstring muscles via surface and indwelling wire electrodes and analyzed for reciprocal inhibition and successive induction, as well as autogenic inhibition (surface electrodes only).

Results:

Reciprocal inhibition was not evident. The results indicated an elevated rather than an inhibited EMG during the antagonist contraction, possibly representing cocontraction. The authors did confirm the presence of successive induction. Autogenic inhibition was also not evident, and the expected inhibition and therefore lower EMG values after muscle contraction were not observed; instead, they were higher than baseline.

Conclusion:

Previous neurophysiological explanations for mechanisms of PNF stretching appear to be inadequate. This study corroborates previous findings that a muscle’s tone increases during its antagonist’s contraction. Other explanations should be considered regarding the mechanism for the effectiveness of the CRAC and CR PNF techniques in a nonneurologically impaired population.

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Allyson M. Carter, Stephen J. Kinzey, Linda F. Chitwood and Judith L Cole

Context:

Proprioceptive neuromuscular facilitation (PNF) is commonly used before competition to increase range of motion. It is not known how it changes muscle response to rapid length changes.

Objective:

To determine whether PNF alters hamstring muscle activity during response to rapid elongation.

Design:

2 X 2 factorial.

Setting:

Laboratory.

Participants:

Twenty-four women; means: 167.27 cm, 58.92 kg, 21.42 y, 18.41% body fat, 21.06 kg/m2 BMI.

intervention:

Measurements before and after either rest or PNF were compared.

Main Outcome Measures:

Average muscle activity immediately after a rapid and unexpected stretch, 3 times pretreatment and posttreatment, averaged into 2 pre-and post- measures.

Results:

PNF caused decreased activity in the biceps femoris during response to a sudden stretch (P = .04). No differences were found in semitendinosus activity (P = .35).

Conclusions:

Decreased muscle activity likely results from acute desensitization of the muscle spindle, which might increase risk of muscle and tendon injury.

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Kimberly Pratt and Richard Bohannon

Context:

Stretching exercise regimens are routinely prescribed to increase range of motion (ROM) and diminish injuries.

Objective:

To examine the effect of a 3-minute passive stretch on ankle-dorsiflexion ROM in a nonpathological population.

Setting:

University laboratory.

Design:

Prospective, randomized, controlled study.

Participants:

24 apparently healthy volunteers.

Interventions:

Subjects stood with their heels suspended from the edge of a platform. The experimental subjects stretched for 3 minutes on 3 consecutive days.

Main Outcome Measures:

Passive ankle-dorsiflexion ROM.

Results:

Ankle-dorsiflexion ROM increased significantly (P < .0005) over the course of each day’s stretch. No significant gains in ankle-dorsiflexion ROM were realized over 3 days.

Conclusions:

These findings suggest the need for further research to determine the stretching frequency and duration that will result in lasting increases in ankle-dorsiflexion ROM

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Jailton Thulher do Rosario, Natalia Santos da Fonseca Martins, Carolina Carneiro Peixinho and Liliam Fernandes Oliveira

This study aimed to determine the effects of a functional training and ankle stretching program in triceps surae torque, passive stiffness index, and in the risk for fall indicators in older adults. Twenty women (73.4 ± 7.3 years) were allocated into an intervention or control group. The 12-week intervention consisted of functional training and calf stretching exercises performed twice a week. Measurements of peak passive and active torque, passive stiffness, maximum dorsiflexion angle, and indexes of risk for falls (Timed Up and Go, functional reach test, QuickScreen-test) were collected. There were no significant differences for all variables, except the maximum dorsiflexion angle, which increased in the intervention group from 33.78 ± 8.57° to 38.89 ± 7.52°. The exercise program was not sufficient to enhance performance on functional tests and decrease the risk for falls in older adults. The significant increase in the maximum dorsiflexion indicates a positive impact of stretching exercises.

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Maxwell Ruby, Chris P. Repka and Paul J. Arciero

Background:

Yoga/Stretching (YS) and functional resistance (FR) training are popular exercise routines. A protein-pacing (PP) diet is a common dietary regimen. Thus, we assessed the effectiveness of a PP diet alone and in combination with either YS or FR to improve body composition and cardiometabolic health.

Methods:

Twenty-seven overweight women (age = 43.2 ± 4.6 years) were randomized into 3 groups: yoga (YS, n = 8) or resistance (FR, n = 10) training (3 days/week) in conjunction with PP diet (50% carbohydrate, 25% protein, and 25% fat) or PP diet-only (PP, n = 9) throughout 12-week study. PP maintained preexisting levels of physical activity. Body weight (BW), total (BF) and abdominal (ABF) body fat, waist circumference (WC), plasma biomarkers, and aerobic fitness (VO2) were measured at baseline and 12 weeks.

Results:

WC and total cholesterol improved in all groups, whereas glycemia tended to improve (P = .06) in S. BF, ABF, and VO2 increased significantly in YS and FR (P < .05). Feelings of vigor increased in YS and tension decreased in FR (P < .05).

Conclusions:

YS training tended to decrease blood glucose compared with FR and PP and is equally effective at enhancing body composition, and aerobic fitness in overweight women providing a strong rationale for further research on YS training.

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Erik A. Wikstrom and Patrick O. McKeon

life scores. 14 Ankle joint mobilizations clearly improve DFROM in those with CAI. 15 , 16 Stretching and plantar massage have also improved DFROM in different populations. 17 , 18 Most recently, a randomized controlled trial (RCT) reported that ankle joint mobilizations, calf stretching, and plantar

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Genki Hatano, Shigeyuki Suzuki, Shingo Matsuo, Satoshi Kataura, Kazuaki Yokoi, Taizan Fukaya, Mitsuhiro Fujiwara, Yuji Asai and Masahiro Iwata

muscle imbalances, which predisposes to muscle injuries, 4 patellar tendinopathy, and patellofemoral pain, 5 and facilitates the development of low back pain. 6 Therefore, obtaining detailed information about the effects of stretching on the hamstring muscles is an important issue that could lead to

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Genki Hatano, Shigeyuki Suzuki, Shingo Matsuo, Satoshi Kataura, Kazuaki Yokoi, Taizan Fukaya, Mitsuhiro Fujiwara, Yuji Asai and Masahiro Iwata

muscle imbalances, which predisposes to muscle injuries, 4 patellar tendinopathy, and patellofemoral pain, 5 and facilitates the development of low back pain. 6 Therefore, obtaining detailed information about the effects of stretching on the hamstring muscles is an important issue that could lead to

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Mack D Rubley, Jody B Brucker, Kenneth L Knight, Mark D Ricard and David O Draper

Objective:

To determine the retention of flexibility 25 days after 5 days of three 30-second stretches.

Design:

A 2 × 4 repeated-measures factorial. Treatment and time were independent variables. The dependent variable was flexibility as measured by a sit-and-reach box.

Measurements:

33 college students were tested before and after stretching for 5 consecutive days and without stretching on days 8 and 30. Control subjects were prone for 15 minutes; stretch subjects received 15 min of diathermy or sham diathermy and then performed three 30-second standing right-hamstring stretches.

Results:

Flexibility was greater on days 5, 8, and 30 than day 1, but days 5, 8, and 30 were not different from each other.

Conclusion:

Gains in flexibility are retained for at least 3 weeks after a stretching program. It also appears that 2 sets of 3 repetitions of a sit-and-reach test is sufficient stimulus to induce long-term flexibility gains.