D. Newham - Academia.edu (original) (raw)
Papers by D. Newham
Journal of Applied Physiology, 2006
A long-lasting fatigue was measured in human biceps muscle, following 40 maximal isokinetic conce... more A long-lasting fatigue was measured in human biceps muscle, following 40 maximal isokinetic concentric or eccentric contractions of the forearm, as the response to single-shock stimuli every minute for 4 h. This protocol allowed new observations on the early time course of long-lasting fatigue. Concentric contractions induced a novel progressive decline to 30.2% (SE 7.8, n = 7) of control at 23 min with complete recovery by 120 min. Eccentric contractions lead initially to a smaller force reduction of similar time course followed by a slower decline to 40.0% (SE 5.1, n = 7) control at 120 min with recovery less than half complete at 4 h. A 50-Hz test stimuli overcame both fatigues, identifying low-frequency fatigue. EMG recordings from the biceps muscle showed moderate (<20%) changes during the fatigue. A visual-tracking task showed no decrement in performance at the time of maximal fatigue of the single-shock response. Because the eccentric contractions have a similar activation...
Nihon Gekakei Rengo Gakkaishi (Journal of Japanese College of Surgeons), 2002
Pain research and clinical management, 1993
Royal Hospital for Neuro-disability, London and Applied Biomedical Research Group, GKT School of ... more Royal Hospital for Neuro-disability, London and Applied Biomedical Research Group, GKT School of Biomedical Sciences, King’s College London Background: The relationship between the size and therefore force-generating capacity of individual abdominal muscles is unknown and may be influenced by various factors. The aim of this study was to investigate the normal relative contribution of individual muscles to total abdominal muscle thickness, and to examine the association with training and low back pain (LBP). Method: Three groups of male subjects (age range 18–30 years) were studied: elite rowers with (n = 10) or without (n = 20) current or previous LBP and age-matched controls (n = 18). Real-time ultrasound imaging was used to measure the external oblique (EO), internal oblique(IO), transversus abdominis (TA) and rectus abdominis (RA) bilaterally. The relative thickness of each muscle was expressed as a percentage of total abdominal muscle thickness. Results: The controls and rowers...
Dose-Response, 2019
The aim of this study was to characterize acceleration transmission and neuromuscular responses t... more The aim of this study was to characterize acceleration transmission and neuromuscular responses to rotational vibration (RV) and vertical vibration (VV) at different frequencies and amplitudes. Methods: Twelve healthy males completed 2 experimental trials (RV vs VV) during which vibration was delivered during either squatting (30 ; RV vs VV) or standing (RV only) with 20, 25, and 30 Hz, at 1.5 and 3.0 mm peak-to-peak amplitude. Vibrationinduced accelerations were assessed with triaxial accelerometers mounted on the platform and bony landmarks at ankle, knee, and lumbar spine. Results: At all frequency/amplitude combinations, accelerations at the ankle were greater during RV (all P < .03) with the greatest difference observed at 30 Hz, 1.5 mm. Transmission of RV was also influenced by body posture (standing vs squatting, P < .03). Irrespective of vibration type, vibration transmission to all skeletal sites was generally greater at higher amplitudes but not at higher frequencies, especially above the ankle joint. Acceleration at the lumbar spine increased with greater vibration amplitude but not frequency and was highest with RV during standing. Conclusions/Implications: The transmission of vibration during whole-body vibration (WBV) is dependent on intensity and direction of vibration as well as body posture. For targeted mechanical loading at the lumbar spine, RV of higher amplitude and lower frequency vibration while standing is recommended. These results will assist with the prescription of WBV to achieve desired levels of mechanical loading at specific sites in the human body.
International Journal of Sports Medicine, 2015
ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically a... more ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically active and inactive individuals during whole-body vibration exercises. Additionally, transmissibility of the vertical acceleration to the head was quantified. 30 active and 28 inactive participants volunteered to stand in a relaxed (20°) and a squat (60°) position on a side-alternating WBV platform that induced vibrations at 16 Hz and 4 mm amplitude. Surface electromyography (sEMG) was measured in selected lower limb muscles and was normalized to the corresponding sEMG recorded during a maximal voluntary contraction. The vertical acceleration on the head was evaluated and divided by the vertical platform acceleration to obtain transmissibility values. Control trials without vibration were also assessed. The outcomes of this study showed that (1) WBV significantly increased muscle activity in the active (absolute increase: +7%, P <0.05) and inactive participants (+8%, P <0.05), (2) with no differences in sEMG increases between the groups (P>0.05). However, (3), transmissibility to the head was greater in the active (0.080) than the inactive participants (0.065, P <0.05). In conclusion, inactive individuals show similar responses in sEMG due to WBV as their active counterparts, but are at lower risk for potential side-effects of vibration exposure.
Medicine & Science in Sports & Exercise, 2003
Purpose: Chronic exertional compartment syndrome (CECS) in the anterior tibial (AT) compartment i... more Purpose: Chronic exertional compartment syndrome (CECS) in the anterior tibial (AT) compartment is generally believed to be the result of reduced venous blood flow caused by restrictive compartments and increased intramuscular pressures. If this is so, then restricting venous flow in the muscles of healthy subjects during exercise should mimic CECS. Methods: This hypothesis was tested in 10 control subjects (aged 19-41 yr, five males) with and without external venous occlusion induced by a sphygmomanometer cuff fitted just below the knee and inflated to 80 mm Hg. Twenty CECS patients (20-39 yr, 16 males) were studied without external occlusion. Subjects performed intermittent, isometric maximal voluntary contractions (MVC) of the AT for 20 min (1.6-s contractions, 0.5 duty cycle). MVC, tetanic force (2 s at 50 Hz), muscle thickness (ultrasound imaging), and pain were measured during exercise and 10 min of recovery. Results: Venous occlusion in the controls induced greater pain, fatigue, and increase in muscle thickness (P Ͻ 0.01). Initially the patients fatigued more slowly than the occluded controls, but at the end of exercise, the fatigue and pain were similar in these two groups. The controls showed a greater increase in muscle size (P ϭ 0.01). Recovery was similar in all three groups, although the size of the patients' muscles recovered rather more slowly. Conclusion: External venous occlusion of the AT muscles in control subjects induces changes very similar to those of CECS patients, although the different time courses indicate that different processes are involved. The AT compartment of CECS patients is capable of distension.
Pain research and clinical management, 1993
Royal Hospital for Neuro-disability, London and Applied Biomedical Research Group, GKT School of ... more Royal Hospital for Neuro-disability, London and Applied Biomedical Research Group, GKT School of Biomedical Sciences, King’s College London Background: The relationship between the size and therefore force-generating capacity of individual abdominal muscles is unknown and may be influenced by various factors. The aim of this study was to investigate the normal relative contribution of individual muscles to total abdominal muscle thickness, and to examine the association with training and low back pain (LBP). Method: Three groups of male subjects (age range 18–30 years) were studied: elite rowers with (n = 10) or without (n = 20) current or previous LBP and age-matched controls (n = 18). Real-time ultrasound imaging was used to measure the external oblique (EO), internal oblique(IO), transversus abdominis (TA) and rectus abdominis (RA) bilaterally. The relative thickness of each muscle was expressed as a percentage of total abdominal muscle thickness. Results: The controls and rowers...
Dose-Response, 2019
The aim of this study was to characterize acceleration transmission and neuromuscular responses t... more The aim of this study was to characterize acceleration transmission and neuromuscular responses to rotational vibration (RV) and vertical vibration (VV) at different frequencies and amplitudes. Methods: Twelve healthy males completed 2 experimental trials (RV vs VV) during which vibration was delivered during either squatting (30 ; RV vs VV) or standing (RV only) with 20, 25, and 30 Hz, at 1.5 and 3.0 mm peak-to-peak amplitude. Vibrationinduced accelerations were assessed with triaxial accelerometers mounted on the platform and bony landmarks at ankle, knee, and lumbar spine. Results: At all frequency/amplitude combinations, accelerations at the ankle were greater during RV (all P < .03) with the greatest difference observed at 30 Hz, 1.5 mm. Transmission of RV was also influenced by body posture (standing vs squatting, P < .03). Irrespective of vibration type, vibration transmission to all skeletal sites was generally greater at higher amplitudes but not at higher frequencies, especially above the ankle joint. Acceleration at the lumbar spine increased with greater vibration amplitude but not frequency and was highest with RV during standing. Conclusions/Implications: The transmission of vibration during whole-body vibration (WBV) is dependent on intensity and direction of vibration as well as body posture. For targeted mechanical loading at the lumbar spine, RV of higher amplitude and lower frequency vibration while standing is recommended. These results will assist with the prescription of WBV to achieve desired levels of mechanical loading at specific sites in the human body.
International Journal of Sports Medicine, 2015
ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically a... more ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically active and inactive individuals during whole-body vibration exercises. Additionally, transmissibility of the vertical acceleration to the head was quantified. 30 active and 28 inactive participants volunteered to stand in a relaxed (20°) and a squat (60°) position on a side-alternating WBV platform that induced vibrations at 16 Hz and 4 mm amplitude. Surface electromyography (sEMG) was measured in selected lower limb muscles and was normalized to the corresponding sEMG recorded during a maximal voluntary contraction. The vertical acceleration on the head was evaluated and divided by the vertical platform acceleration to obtain transmissibility values. Control trials without vibration were also assessed. The outcomes of this study showed that (1) WBV significantly increased muscle activity in the active (absolute increase: +7%, P <0.05) and inactive participants (+8%, P <0.05), (2) with no differences in sEMG increases between the groups (P>0.05). However, (3), transmissibility to the head was greater in the active (0.080) than the inactive participants (0.065, P <0.05). In conclusion, inactive individuals show similar responses in sEMG due to WBV as their active counterparts, but are at lower risk for potential side-effects of vibration exposure.
Medicine & Science in Sports & Exercise, 2003
Purpose: Chronic exertional compartment syndrome (CECS) in the anterior tibial (AT) compartment i... more Purpose: Chronic exertional compartment syndrome (CECS) in the anterior tibial (AT) compartment is generally believed to be the result of reduced venous blood flow caused by restrictive compartments and increased intramuscular pressures. If this is so, then restricting venous flow in the muscles of healthy subjects during exercise should mimic CECS. Methods: This hypothesis was tested in 10 control subjects (aged 19-41 yr, five males) with and without external venous occlusion induced by a sphygmomanometer cuff fitted just below the knee and inflated to 80 mm Hg. Twenty CECS patients (20-39 yr, 16 males) were studied without external occlusion. Subjects performed intermittent, isometric maximal voluntary contractions (MVC) of the AT for 20 min (1.6-s contractions, 0.5 duty cycle). MVC, tetanic force (2 s at 50 Hz), muscle thickness (ultrasound imaging), and pain were measured during exercise and 10 min of recovery. Results: Venous occlusion in the controls induced greater pain, fatigue, and increase in muscle thickness (P Ͻ 0.01). Initially the patients fatigued more slowly than the occluded controls, but at the end of exercise, the fatigue and pain were similar in these two groups. The controls showed a greater increase in muscle size (P ϭ 0.01). Recovery was similar in all three groups, although the size of the patients' muscles recovered rather more slowly. Conclusion: External venous occlusion of the AT muscles in control subjects induces changes very similar to those of CECS patients, although the different time courses indicate that different processes are involved. The AT compartment of CECS patients is capable of distension.
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2005
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2005
Introduction. Because sideways falls are common in elderly persons, we devised a method to measur... more Introduction. Because sideways falls are common in elderly persons, we devised a method to measure variable lateral movements of the thorax with respect to foot position during normal walking. Methods. Movements of the ankles and shoulders were measured during walking a distance of 9 m. Two age groups were studied: young (n ¼ 17, 6 male, mean age 27.3 years) and older (n ¼ 21, 13 male, mean age 72.7 years) people. During walking, the path followed in the horizontal plane by the midpoint between the two shoulders was compared to the line connecting successive positions of the ankles during stance. Lateral deviations between these two paths were divided into a regular component (average of about 30 strides) and a variable component (the difference between the deviation during each stride and the average). Lateral sway was also observed while standing with eyes open for 1 minute. Results. The older group had more lateral movement during walking in the variable component (p ¼ .006) and a nonsignificant trend (p ¼ .054) in the same direction in the regular component. Eight of the older participants had a value for the variable component greater than the 95% confidence limit for the young participants. Only two of the older participants had a standing sway outside the confidence limit for the young participants. The variable component was associated with variability in stride width. Discussion. The variable component of lateral sway during walking provides good discrimination between age groups, as does variability in step width. It remains to be seen whether these variables are different in fallers and nonfallers.
European Journal of Applied Physiology, 2003
There are a number of similarities between chronic exertional compartment syndrome (CECS) and the... more There are a number of similarities between chronic exertional compartment syndrome (CECS) and the effects of high force eccentric contractions in healthy controls. We hypothesised that CECS patients would be particularly susceptible to pain, fatigue and swelling after eccentric exercise. Ten CECS patients [aged 30.3 (8.0) years, mean (SD)], 7 males) and 14 healthy controls [aged 32.3 (9.0) years, 7 males] performed 40 maximal eccentric contractions of the anterior tibial muscles at an angular velocity of 90 o s-1. Maximal voluntary isometric contractions (MVC), force generated by electrical stimulation at 10 Hz and 50 Hz and muscle thickness (measured by real-time ultrasound scanning) were measured before exercise and for 10 min afterwards. Ratings of pain and tenderness were made before exercise, then 24 h and 48 h later. The two groups were comparable for initial isometric strength and muscle size. MVC force immediately after exercise fell to 90 (2.5)% [mean (SEM)] in patients and 86.5 (2.4)% in controls (P<0.0005 for both groups) and had not recovered after 10 min. Preferential loss of force at the low stimulation frequency occurred in both groups to a similar extent (20%, P<0.0005) and continued to decline over 10 min of recovery. There was no significant change in muscle thickness in either group. Only mild pain and tenderness were reported by the controls. The patients showed great individual variation but their mean pain scores were significantly higher during dorsiflexion and palpation (P<0.05) 24 h after exercise. After 48 h the patients reported more pain during dorsiflexion (P=0.005), plantarflexion (P<0.05) and palpation (P<0.05). These results suggest that some, but not all, CECS patients may be more susceptible to the pain associated with eccentric contractions that is thought to be the cause of damage and inflammation of connective tissue. Keywords Chronic exertional compartment syndrome AE Eccentric exercise AE Muscle pain AE Muscle fatigue AE Muscle damage
Annals of the Royal College of Surgeons of England, 1990
This study investigates the role of motivation in voluntary strength measurements during the post... more This study investigates the role of motivation in voluntary strength measurements during the postoperative period. Thirty patients underwent surgery which was deemed minor, intermediate or major in severity. Before operation and on the 4th postoperative day measurement of grip strength, maximal voluntary and maximal tetanic (stimulated) contraction of adductor pollicis and assessment of mood were recorded. These investigations were also repeated on the 7th postoperative day in those who had major surgery. No patient had postoperative complications. Minor surgery had no influence on any of the values. Those who underwent major surgery showed significant reductions in grip strength, maximal voluntary contraction and mood; however, maximal tetanic contraction was unaffected. The results in the intermediate group were similar to the major group, although mood depression was less marked. Real strength of a hand muscle appears to be unaltered even by major surgery, but voluntary muscle fo...
SPINE, 2016
Study Design. Systematic review. Objective. To review the evidence regarding the mechanism of act... more Study Design. Systematic review. Objective. To review the evidence regarding the mechanism of action of mobilizations. Summary of Background Data. Spinal mobilizations-low velocity passive oscillatory movements-reduce spinal pain in some patient subgroups. Identifying patients likely to respond remains a challenge since mobilizations' mechanism(s) of action are unclear. Methods. Medline, Web of Science, Cinahl, Embase, and Scopus databases were searched for relevant studies. Reference lists of included studies were hand searched. Studies were included if the intervention was passive spinal mobilizations, participants were symptomatic, and outcomes evaluated possible mechanisms of action. Methodological quality was independently assessed by two assessors using a modified Cochrane Back Review Group tool. Results. Twenty-four studies were included in the review. Four were classified high risk, 14 moderate risk, and four low risk of bias. Commonest methodological limitations were lack of participant blinding, adequate randomization and allocation concealment, and sample size calculation. Evidence suggests that spinal mobilizations cause neurophysiological effects resulting in hypoalgesia (local and/or distal to mobilization site), sympathoexcitation, and improved muscle function. Mobilizations have no effect on temperature pain threshold. Three of four studies reported reduction in spinal stiffness, heterogeneous in location and timing. There is limited evidence (one study in each case) to suggest that mobilizations produce increased nociceptive flexion reflex threshold, improved posture, decreased concentration of substance P in saliva, and improved sway index measured in cervical extension. Evidence does not support an effect on segmental vertebral movement. Two studies investigated correlations between hypoalgesia and mechanism: one found a correlation with sympathoexcitatory changes, whereas the other found no correlation with change in stiffness. Conclusion. These findings suggest involvement of an endogenous pain inhibition system mediated by the central nervous system, although this is yet to be investigated directly. There is limited evidence regarding other possible mechanisms.
Journal of Applied Physiology, 2006
A long-lasting fatigue was measured in human biceps muscle, following 40 maximal isokinetic conce... more A long-lasting fatigue was measured in human biceps muscle, following 40 maximal isokinetic concentric or eccentric contractions of the forearm, as the response to single-shock stimuli every minute for 4 h. This protocol allowed new observations on the early time course of long-lasting fatigue. Concentric contractions induced a novel progressive decline to 30.2% (SE 7.8, n = 7) of control at 23 min with complete recovery by 120 min. Eccentric contractions lead initially to a smaller force reduction of similar time course followed by a slower decline to 40.0% (SE 5.1, n = 7) control at 120 min with recovery less than half complete at 4 h. A 50-Hz test stimuli overcame both fatigues, identifying low-frequency fatigue. EMG recordings from the biceps muscle showed moderate (<20%) changes during the fatigue. A visual-tracking task showed no decrement in performance at the time of maximal fatigue of the single-shock response. Because the eccentric contractions have a similar activation...
Nihon Gekakei Rengo Gakkaishi (Journal of Japanese College of Surgeons), 2002
Pain research and clinical management, 1993
Royal Hospital for Neuro-disability, London and Applied Biomedical Research Group, GKT School of ... more Royal Hospital for Neuro-disability, London and Applied Biomedical Research Group, GKT School of Biomedical Sciences, King’s College London Background: The relationship between the size and therefore force-generating capacity of individual abdominal muscles is unknown and may be influenced by various factors. The aim of this study was to investigate the normal relative contribution of individual muscles to total abdominal muscle thickness, and to examine the association with training and low back pain (LBP). Method: Three groups of male subjects (age range 18–30 years) were studied: elite rowers with (n = 10) or without (n = 20) current or previous LBP and age-matched controls (n = 18). Real-time ultrasound imaging was used to measure the external oblique (EO), internal oblique(IO), transversus abdominis (TA) and rectus abdominis (RA) bilaterally. The relative thickness of each muscle was expressed as a percentage of total abdominal muscle thickness. Results: The controls and rowers...
Dose-Response, 2019
The aim of this study was to characterize acceleration transmission and neuromuscular responses t... more The aim of this study was to characterize acceleration transmission and neuromuscular responses to rotational vibration (RV) and vertical vibration (VV) at different frequencies and amplitudes. Methods: Twelve healthy males completed 2 experimental trials (RV vs VV) during which vibration was delivered during either squatting (30 ; RV vs VV) or standing (RV only) with 20, 25, and 30 Hz, at 1.5 and 3.0 mm peak-to-peak amplitude. Vibrationinduced accelerations were assessed with triaxial accelerometers mounted on the platform and bony landmarks at ankle, knee, and lumbar spine. Results: At all frequency/amplitude combinations, accelerations at the ankle were greater during RV (all P < .03) with the greatest difference observed at 30 Hz, 1.5 mm. Transmission of RV was also influenced by body posture (standing vs squatting, P < .03). Irrespective of vibration type, vibration transmission to all skeletal sites was generally greater at higher amplitudes but not at higher frequencies, especially above the ankle joint. Acceleration at the lumbar spine increased with greater vibration amplitude but not frequency and was highest with RV during standing. Conclusions/Implications: The transmission of vibration during whole-body vibration (WBV) is dependent on intensity and direction of vibration as well as body posture. For targeted mechanical loading at the lumbar spine, RV of higher amplitude and lower frequency vibration while standing is recommended. These results will assist with the prescription of WBV to achieve desired levels of mechanical loading at specific sites in the human body.
International Journal of Sports Medicine, 2015
ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically a... more ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically active and inactive individuals during whole-body vibration exercises. Additionally, transmissibility of the vertical acceleration to the head was quantified. 30 active and 28 inactive participants volunteered to stand in a relaxed (20°) and a squat (60°) position on a side-alternating WBV platform that induced vibrations at 16 Hz and 4 mm amplitude. Surface electromyography (sEMG) was measured in selected lower limb muscles and was normalized to the corresponding sEMG recorded during a maximal voluntary contraction. The vertical acceleration on the head was evaluated and divided by the vertical platform acceleration to obtain transmissibility values. Control trials without vibration were also assessed. The outcomes of this study showed that (1) WBV significantly increased muscle activity in the active (absolute increase: +7%, P <0.05) and inactive participants (+8%, P <0.05), (2) with no differences in sEMG increases between the groups (P>0.05). However, (3), transmissibility to the head was greater in the active (0.080) than the inactive participants (0.065, P <0.05). In conclusion, inactive individuals show similar responses in sEMG due to WBV as their active counterparts, but are at lower risk for potential side-effects of vibration exposure.
Medicine & Science in Sports & Exercise, 2003
Purpose: Chronic exertional compartment syndrome (CECS) in the anterior tibial (AT) compartment i... more Purpose: Chronic exertional compartment syndrome (CECS) in the anterior tibial (AT) compartment is generally believed to be the result of reduced venous blood flow caused by restrictive compartments and increased intramuscular pressures. If this is so, then restricting venous flow in the muscles of healthy subjects during exercise should mimic CECS. Methods: This hypothesis was tested in 10 control subjects (aged 19-41 yr, five males) with and without external venous occlusion induced by a sphygmomanometer cuff fitted just below the knee and inflated to 80 mm Hg. Twenty CECS patients (20-39 yr, 16 males) were studied without external occlusion. Subjects performed intermittent, isometric maximal voluntary contractions (MVC) of the AT for 20 min (1.6-s contractions, 0.5 duty cycle). MVC, tetanic force (2 s at 50 Hz), muscle thickness (ultrasound imaging), and pain were measured during exercise and 10 min of recovery. Results: Venous occlusion in the controls induced greater pain, fatigue, and increase in muscle thickness (P Ͻ 0.01). Initially the patients fatigued more slowly than the occluded controls, but at the end of exercise, the fatigue and pain were similar in these two groups. The controls showed a greater increase in muscle size (P ϭ 0.01). Recovery was similar in all three groups, although the size of the patients' muscles recovered rather more slowly. Conclusion: External venous occlusion of the AT muscles in control subjects induces changes very similar to those of CECS patients, although the different time courses indicate that different processes are involved. The AT compartment of CECS patients is capable of distension.
Pain research and clinical management, 1993
Royal Hospital for Neuro-disability, London and Applied Biomedical Research Group, GKT School of ... more Royal Hospital for Neuro-disability, London and Applied Biomedical Research Group, GKT School of Biomedical Sciences, King’s College London Background: The relationship between the size and therefore force-generating capacity of individual abdominal muscles is unknown and may be influenced by various factors. The aim of this study was to investigate the normal relative contribution of individual muscles to total abdominal muscle thickness, and to examine the association with training and low back pain (LBP). Method: Three groups of male subjects (age range 18–30 years) were studied: elite rowers with (n = 10) or without (n = 20) current or previous LBP and age-matched controls (n = 18). Real-time ultrasound imaging was used to measure the external oblique (EO), internal oblique(IO), transversus abdominis (TA) and rectus abdominis (RA) bilaterally. The relative thickness of each muscle was expressed as a percentage of total abdominal muscle thickness. Results: The controls and rowers...
Dose-Response, 2019
The aim of this study was to characterize acceleration transmission and neuromuscular responses t... more The aim of this study was to characterize acceleration transmission and neuromuscular responses to rotational vibration (RV) and vertical vibration (VV) at different frequencies and amplitudes. Methods: Twelve healthy males completed 2 experimental trials (RV vs VV) during which vibration was delivered during either squatting (30 ; RV vs VV) or standing (RV only) with 20, 25, and 30 Hz, at 1.5 and 3.0 mm peak-to-peak amplitude. Vibrationinduced accelerations were assessed with triaxial accelerometers mounted on the platform and bony landmarks at ankle, knee, and lumbar spine. Results: At all frequency/amplitude combinations, accelerations at the ankle were greater during RV (all P < .03) with the greatest difference observed at 30 Hz, 1.5 mm. Transmission of RV was also influenced by body posture (standing vs squatting, P < .03). Irrespective of vibration type, vibration transmission to all skeletal sites was generally greater at higher amplitudes but not at higher frequencies, especially above the ankle joint. Acceleration at the lumbar spine increased with greater vibration amplitude but not frequency and was highest with RV during standing. Conclusions/Implications: The transmission of vibration during whole-body vibration (WBV) is dependent on intensity and direction of vibration as well as body posture. For targeted mechanical loading at the lumbar spine, RV of higher amplitude and lower frequency vibration while standing is recommended. These results will assist with the prescription of WBV to achieve desired levels of mechanical loading at specific sites in the human body.
International Journal of Sports Medicine, 2015
ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically a... more ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically active and inactive individuals during whole-body vibration exercises. Additionally, transmissibility of the vertical acceleration to the head was quantified. 30 active and 28 inactive participants volunteered to stand in a relaxed (20°) and a squat (60°) position on a side-alternating WBV platform that induced vibrations at 16 Hz and 4 mm amplitude. Surface electromyography (sEMG) was measured in selected lower limb muscles and was normalized to the corresponding sEMG recorded during a maximal voluntary contraction. The vertical acceleration on the head was evaluated and divided by the vertical platform acceleration to obtain transmissibility values. Control trials without vibration were also assessed. The outcomes of this study showed that (1) WBV significantly increased muscle activity in the active (absolute increase: +7%, P <0.05) and inactive participants (+8%, P <0.05), (2) with no differences in sEMG increases between the groups (P>0.05). However, (3), transmissibility to the head was greater in the active (0.080) than the inactive participants (0.065, P <0.05). In conclusion, inactive individuals show similar responses in sEMG due to WBV as their active counterparts, but are at lower risk for potential side-effects of vibration exposure.
Medicine & Science in Sports & Exercise, 2003
Purpose: Chronic exertional compartment syndrome (CECS) in the anterior tibial (AT) compartment i... more Purpose: Chronic exertional compartment syndrome (CECS) in the anterior tibial (AT) compartment is generally believed to be the result of reduced venous blood flow caused by restrictive compartments and increased intramuscular pressures. If this is so, then restricting venous flow in the muscles of healthy subjects during exercise should mimic CECS. Methods: This hypothesis was tested in 10 control subjects (aged 19-41 yr, five males) with and without external venous occlusion induced by a sphygmomanometer cuff fitted just below the knee and inflated to 80 mm Hg. Twenty CECS patients (20-39 yr, 16 males) were studied without external occlusion. Subjects performed intermittent, isometric maximal voluntary contractions (MVC) of the AT for 20 min (1.6-s contractions, 0.5 duty cycle). MVC, tetanic force (2 s at 50 Hz), muscle thickness (ultrasound imaging), and pain were measured during exercise and 10 min of recovery. Results: Venous occlusion in the controls induced greater pain, fatigue, and increase in muscle thickness (P Ͻ 0.01). Initially the patients fatigued more slowly than the occluded controls, but at the end of exercise, the fatigue and pain were similar in these two groups. The controls showed a greater increase in muscle size (P ϭ 0.01). Recovery was similar in all three groups, although the size of the patients' muscles recovered rather more slowly. Conclusion: External venous occlusion of the AT muscles in control subjects induces changes very similar to those of CECS patients, although the different time courses indicate that different processes are involved. The AT compartment of CECS patients is capable of distension.
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2005
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2005
Introduction. Because sideways falls are common in elderly persons, we devised a method to measur... more Introduction. Because sideways falls are common in elderly persons, we devised a method to measure variable lateral movements of the thorax with respect to foot position during normal walking. Methods. Movements of the ankles and shoulders were measured during walking a distance of 9 m. Two age groups were studied: young (n ¼ 17, 6 male, mean age 27.3 years) and older (n ¼ 21, 13 male, mean age 72.7 years) people. During walking, the path followed in the horizontal plane by the midpoint between the two shoulders was compared to the line connecting successive positions of the ankles during stance. Lateral deviations between these two paths were divided into a regular component (average of about 30 strides) and a variable component (the difference between the deviation during each stride and the average). Lateral sway was also observed while standing with eyes open for 1 minute. Results. The older group had more lateral movement during walking in the variable component (p ¼ .006) and a nonsignificant trend (p ¼ .054) in the same direction in the regular component. Eight of the older participants had a value for the variable component greater than the 95% confidence limit for the young participants. Only two of the older participants had a standing sway outside the confidence limit for the young participants. The variable component was associated with variability in stride width. Discussion. The variable component of lateral sway during walking provides good discrimination between age groups, as does variability in step width. It remains to be seen whether these variables are different in fallers and nonfallers.
European Journal of Applied Physiology, 2003
There are a number of similarities between chronic exertional compartment syndrome (CECS) and the... more There are a number of similarities between chronic exertional compartment syndrome (CECS) and the effects of high force eccentric contractions in healthy controls. We hypothesised that CECS patients would be particularly susceptible to pain, fatigue and swelling after eccentric exercise. Ten CECS patients [aged 30.3 (8.0) years, mean (SD)], 7 males) and 14 healthy controls [aged 32.3 (9.0) years, 7 males] performed 40 maximal eccentric contractions of the anterior tibial muscles at an angular velocity of 90 o s-1. Maximal voluntary isometric contractions (MVC), force generated by electrical stimulation at 10 Hz and 50 Hz and muscle thickness (measured by real-time ultrasound scanning) were measured before exercise and for 10 min afterwards. Ratings of pain and tenderness were made before exercise, then 24 h and 48 h later. The two groups were comparable for initial isometric strength and muscle size. MVC force immediately after exercise fell to 90 (2.5)% [mean (SEM)] in patients and 86.5 (2.4)% in controls (P<0.0005 for both groups) and had not recovered after 10 min. Preferential loss of force at the low stimulation frequency occurred in both groups to a similar extent (20%, P<0.0005) and continued to decline over 10 min of recovery. There was no significant change in muscle thickness in either group. Only mild pain and tenderness were reported by the controls. The patients showed great individual variation but their mean pain scores were significantly higher during dorsiflexion and palpation (P<0.05) 24 h after exercise. After 48 h the patients reported more pain during dorsiflexion (P=0.005), plantarflexion (P<0.05) and palpation (P<0.05). These results suggest that some, but not all, CECS patients may be more susceptible to the pain associated with eccentric contractions that is thought to be the cause of damage and inflammation of connective tissue. Keywords Chronic exertional compartment syndrome AE Eccentric exercise AE Muscle pain AE Muscle fatigue AE Muscle damage
Annals of the Royal College of Surgeons of England, 1990
This study investigates the role of motivation in voluntary strength measurements during the post... more This study investigates the role of motivation in voluntary strength measurements during the postoperative period. Thirty patients underwent surgery which was deemed minor, intermediate or major in severity. Before operation and on the 4th postoperative day measurement of grip strength, maximal voluntary and maximal tetanic (stimulated) contraction of adductor pollicis and assessment of mood were recorded. These investigations were also repeated on the 7th postoperative day in those who had major surgery. No patient had postoperative complications. Minor surgery had no influence on any of the values. Those who underwent major surgery showed significant reductions in grip strength, maximal voluntary contraction and mood; however, maximal tetanic contraction was unaffected. The results in the intermediate group were similar to the major group, although mood depression was less marked. Real strength of a hand muscle appears to be unaltered even by major surgery, but voluntary muscle fo...
SPINE, 2016
Study Design. Systematic review. Objective. To review the evidence regarding the mechanism of act... more Study Design. Systematic review. Objective. To review the evidence regarding the mechanism of action of mobilizations. Summary of Background Data. Spinal mobilizations-low velocity passive oscillatory movements-reduce spinal pain in some patient subgroups. Identifying patients likely to respond remains a challenge since mobilizations' mechanism(s) of action are unclear. Methods. Medline, Web of Science, Cinahl, Embase, and Scopus databases were searched for relevant studies. Reference lists of included studies were hand searched. Studies were included if the intervention was passive spinal mobilizations, participants were symptomatic, and outcomes evaluated possible mechanisms of action. Methodological quality was independently assessed by two assessors using a modified Cochrane Back Review Group tool. Results. Twenty-four studies were included in the review. Four were classified high risk, 14 moderate risk, and four low risk of bias. Commonest methodological limitations were lack of participant blinding, adequate randomization and allocation concealment, and sample size calculation. Evidence suggests that spinal mobilizations cause neurophysiological effects resulting in hypoalgesia (local and/or distal to mobilization site), sympathoexcitation, and improved muscle function. Mobilizations have no effect on temperature pain threshold. Three of four studies reported reduction in spinal stiffness, heterogeneous in location and timing. There is limited evidence (one study in each case) to suggest that mobilizations produce increased nociceptive flexion reflex threshold, improved posture, decreased concentration of substance P in saliva, and improved sway index measured in cervical extension. Evidence does not support an effect on segmental vertebral movement. Two studies investigated correlations between hypoalgesia and mechanism: one found a correlation with sympathoexcitatory changes, whereas the other found no correlation with change in stiffness. Conclusion. These findings suggest involvement of an endogenous pain inhibition system mediated by the central nervous system, although this is yet to be investigated directly. There is limited evidence regarding other possible mechanisms.