The purpose of this study was to document the muscle activity, spine motion, spine load, and stiffness during several movement-based or "functional" exercises and to assess the effect of technique change. Eight subjects, all healthy men from a university population, were instrumented to obtain surface electromyography of selected trunk and hip muscles, together with video analysis and electromagnetic lumbar spine position sensor to track spine posture. Exercises included a walkout in the sagittal plane that compared an upright form against a wall with those performed on the floor, overhead cable pushes, lateral cable walkouts, the good morning exercise, and the bowler's squat. Generally, muscle activation levels were quite modest even though the tasks were quite strenuous in many cases. Even though similar joint moments were required in different exercises, the pattern of activity between muscles was different. Abdominal bracing increased spine stiffness at the expense of more spine load. Thus, muscle activity seems to be constrained in "functional" exercises. There are several possible reasons for this. Single muscles cannot be activated to 100% of the maximum voluntary contraction in functional exercises because this would upset the balance of moments about the 3 orthopedic axes of the spine, or it would upset the balance of stiffening muscles around the spine required to ensure stability of the spinal column. The one exception was the floor walkout, which resulted in full activation of the rectus abdominis; however, this was a sagittal plane task without the joint moment constraints of multiplanar exercise. Therefore, maximal muscle activity is observed during single-plane tasks, but muscle activation levels were constrained during functional tasks. Thus, strength training muscles may not help in "functional multiplanar" tasks. These data can be used to assist decisions regarding the selection of exercises, specifically choices regarding the starting challenge, progression, exercise form, and possibly corrective technique for those who have spine concerns, or those simply looking for performance enhancement.
"and right thoracic erector spinae 5 cm lateral to spinous process T9 (TES) (Konrad, 2005; McGill et al., 2009). Lumbar flexion was calculated by placing 25.4 mm spherical markers on T11, L1, and S2, and a 14.0 mm marker on the ASIS (Kuo, Tully & Galea, 2009a; Kuo, Tully & Galea, 2009b; Kuo, Tully & Galea, 2009c). "
[Show abstract][Hide abstract] ABSTRACT: Many strength and conditioning coaches utilize the good morning (GM) to strengthen the hamstrings and spinal erectors. However, little research exists on its electromyography (EMG) activity and kinematics, and how these variables change as a function of load. The purpose of this investigation was to examine how estimated hamstring length, integrated EMG (IEMG) activity of the hamstrings and spinal erectors, and kinematics of the lumbar spine, hip, knee, and ankle are affected by changes in load. Fifteen trained male participants (age = 24.6 ± 5.3 years; body mass = 84.7 ± 11.3 kg; height = 180.9 ± 6.8 cm) were recruited for this study. Participants performed five sets of the GM, utilizing 50, 60, 70, 80, and 90% of one-repetition maximum (1RM) in a randomized fashion. IEMG activity of hamstrings and spinal erectors tended to increase with load. Knee flexion increased with load on all trials. Estimated hamstring length decreased with load. However, lumbar flexion, hip flex-ion, and plantar flexion experienced no remarkable changes between trials. These data provide insight as to how changing the load of the GM affects EMG activity, kinematic variables, and estimated hamstring length. Implications for hamstring injury prevention are discussed. More research is needed for further insight as to how load affects EMG activity and kinematics of other exercises.
[Show abstract][Hide abstract] ABSTRACT: THIS REVIEW ARTICLE RECOGNIZES THE UNIQUE FUNCTION OF THE CORE MUSCULATURE. IN MANY REAL LIFE ACTIVITIES, THESE MUSCLES ACT TO STIFFEN THE TORSO AND FUNCTION PRIMARILY TO PREVENT MOTION. THIS IS A FUNDAMENTALLY DIFFERENT FUNCTION FROM THOSE MUSCLES OF THE LIMBS, WHICH CREATE MOTION. BY STIFFENING THE TORSO, POWER GENERATED AT THE HIPS IS TRANSMITTED MORE EFFECTIVELY BY THE CORE. RECOGNIZING THIS UNIQUENESS, IMPLICATIONS FOR EXERCISE PROGRAM DESIGN ARE DISCUSSED USING PROGRESSIONS BEGINNING WITH CORRECTIVE AND THERAPEUTIC EXERCISES THROUGH STABILITY/MOBILITY, ENDURANCE, STRENGTH AND POWER STAGES, TO ASSIST THE PERSONAL TRAINER WITH A BROAD SPECTRUM OF CLIENTS.
[Show abstract][Hide abstract] ABSTRACT: STUDY DESIGN.: Meta-analysis of randomized, controlled trials. OBJECTIVE.: To determine the short-term, intermediate, and long-term effectiveness of MCE, with regard to pain and disability, in patients with chronic and recurrent low-back pain. SUMMARY OF BACKGROUND DATA.: Previous meta-analyses have shown no difference between the effects of MCE and general exercise in the treatment of low back pain. Several high quality studies on this topic have been published lately, warranting a new meta-analysis. METHODS.: We searched electronic databases up to October 2011 for randomized controlled trials clearly distinguishing MCE from other treatments. We extracted pain and disability outcomes and converted them to a 0 to 100 scale. We used the RevMan5 (Nordic Cochrane Centre, Copenhagen, Denmark) software to perform pooled analyses to determine the weighted mean differences (WMDs) between MCE and 5 different control interventions. RESULTS.: Sixteen studies were included. The pooled results favored MCE compared with general exercise with regard to disability during all time periods (improvement in WMDs ranged from -4.65 to -4.86), and with regard to pain in the short and intermediate term (WMDs were -7.80 and -6.06, respectively). Compared with spinal manual therapy, MCE was superior with regard to disability during all time periods (the WMDs ranged between -5.27 and -6.12), but not with regard to pain. Furthermore, MCE was superior to minimal intervention during all time periods with regard to both pain (the WMDs ranged between -10.18 and -13.32) and disability (the WMDs ranged between -5.62 and -9.00). CONCLUSION.: In patients with chronic and recurrent low back pain, MCE seem to be superior to several other treatments. More studies are, however, needed to investigate what subgroups of patients experiencing LBP respond best to MCE.
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