The treatment of choice for tendinopathies is eccentric reeducation. Although the clinical result... more The treatment of choice for tendinopathies is eccentric reeducation. Although the clinical results appear favorable, the biomechanical changes to the tissue are not yet clear. Even if the mechanotransduction theory is commonly accepted, the physiology of tendons is not clearly understood. We aimed to better define the biomechanical and histological changes that affect healthy tendon after eccentric and concentric training. This study compared the effects of two methods of training (eccentric [E] training and concentric [C] training) with untrained (U) rats. The animals were trained over a period of 5 weeks. The tricipital, patellar, and Achilles tendons were removed, measured and a tensile test until failure was performed. A histological analysis (hematoxylin and eosin and Masson's trichrome stains) was also realized. There was a significant increase in the rupture force of the patellar and tricipital tendons between the U and E groups. The tricipital tendons in the control group presented a significantly smaller cross-sectional area than the E-and C-trained groups, but none was constated between E and C groups. No significant difference was observed for the mechanical stress between the three groups for all three tendons. Histological studies demonstrated the development of a greater number of blood vessels and a larger quantity of collagen in the E group. The mechanical properties of tendons in rats improve after specific training, especially following eccentric training. Our results partly explained how mechanical loading, especially in eccentric mode, could improve the healing of tendon. ß
The Journal of sports medicine and physical fitness, Jan 10, 2014
The aim of this study was to compare tennis players with and without low back pain (LBP) and heal... more The aim of this study was to compare tennis players with and without low back pain (LBP) and healthy sedentary participants regarding the trunk muscle strength and flexibility. Thirty--eight male elite tennis players and 22 healthy sedentary male students (24.8 ± 4.0 years) participated in this investigation. Tennis players were divided into two groups: 11 players (27.8 ± 5.5 years) with current LBP and 27 players (24.3 ± 5.9 years) without LBP. Maximal isometric strength of trunk extensor, rotator, flexor and lateralflexor muscles was assessed by means of specific trunk dynamometers. Pelvic and lumbar flexion mobility were measured by means of inclinometer technique. Comparison of tennis players with and without LBP revealed no significant difference regarding trunk muscle strength and ratio or lumbar spine flexibility (all p>0.05). In comparison with sedentary subjects, the tennis players showed a sport--specific profile determined by a non--dominant trunk lateralflexors (p=0.0...
Annales de réadaptation et de médecine physique : revue scientifique de la Société française de rééducation fonctionnelle de réadaptation et de médecine physique, 2007
The goals of this paper were to define the concept of instability, to describe the way it can be ... more The goals of this paper were to define the concept of instability, to describe the way it can be assessed, to report on impairments of the spine stabilization system in patients with low back pain (LBP), to cite the recommended exercises and, lastly, to examine the results of programs based on lumbar stabilization. Patients suffering from lumbar instability appear to belong to a particular subgroup of subjects with LBP. In the literature, several definitions of lumbar instability have been proposed. Radiological instability, for instance, differs from functional instability. Diagnosis remains difficult: the relevance of static and dynamic radiographs appears limited whereas several signs and clinical instability tests have been described in the literature but remain controversial. The functional stability system of the spine consists of three interdependent components: the passive, the active and the neuromuscular subsystems. The benefits of lumbar stabilization programs for LBP pat...
Electrical stimulation (ES) and voluntary contraction (VC) were compared in the quadriceps muscle... more Electrical stimulation (ES) and voluntary contraction (VC) were compared in the quadriceps muscle of ten male volunteers. In both modes, a workload corresponding to 20% of maximal voluntary contraction was applied during 64 isometric contraction (5.5 s)-relaxation (5.5 s) cycles. The protocols were performed in a 1.5 T whole-body magnet. The Pi/PCr ratio and the intracellular pH (pHi) were monitored by 31P NMR spectroscopy during baseline, exercise and recovery periods, in a superficial region of the vastus medialis. During baseline, the Pi/PCr ratio (0.12 vs. 0.10) and the pHi (7.01 vs. 7.00) were comparable in both conditions. During exercise, the Pi/PCr ratio was higher (0.36 vs. 0.14) and the pHi was lower (6.85 vs. 7.07) during ES than during VC. For the same external work production, these results reflect a different metabolic solicitation in the ES quadriceps than in the VC ones.
Introduction: Joint hypermobility involves an increased range of motion compared to normal amplit... more Introduction: Joint hypermobility involves an increased range of motion compared to normal amplitudes for the same age, sex and ethnic group. Patients with hypermobility suffer from joints problems and chronic pain is the most frequently reported symptom. Eccentric muscle strengthening could be very important to protect hypermobile joints.
The purpose of this study was to estimate the effects of intense and regular physical activity on... more The purpose of this study was to estimate the effects of intense and regular physical activity on locomotor system modifications. Tennis, with its unilateral solicitations, allows a more precise examination of specific localized development. Ten professional tennis players were compared with sedentary age-matched students. Muscular modifications were observed, mainly in the forearm circumference. The dominant side forearm circumference was 13% larger than the opposite side. Asymmetry was less in the upper arm and insignificant in the thorax and vertebra. Deep modifications in bone mineral content (BMC) were investigated by isotopic techniques, based on differential photon attenuation in bone and soft tissue of the forearm. Bone density was markedly increased in professional tennis players. Even in the nondominant side, radius BMC was 1.18 g HA/cm, 15% higher than in sedentary control students. The difference was yet larger in the dominant mid-radius, reaching 1.47 g HA/cm. The same differences were observed for the ulna and involved both cortical and trabecular bone. In the control group of sedentary students, no significant difference was noted between the two upper limbs. This study clearly demonstrates the positive correlation between exercise and bone mineralization. The precise mechanical constraints optimizing the favorable effect in the most efficient way should be studied.
The first test for evaluating the isometric endurance of trunk extensor muscles was described by ... more The first test for evaluating the isometric endurance of trunk extensor muscles was described by Hansen in 1964. In 1984, following a study by Biering-Sorensen, this test became known as the "Sorensen test" and gained considerable popularity as a tool reported to predict low back pain within the next year in males. The test consists in measuring the amount of time a person can hold the unsupported upper body in a horizontal prone position with the lower body fixed to the examining table. This test has been used in many studies, either in its original version or as variants. Although its discriminative validity, reproducibility, and safety seem good, debate continues to surround its ability to predict low back pain; in addition, the gender-related difference in position-holding time remains unexplained and the influence of body weight unclear. A contribution of the hip extensor muscles to position holding has been established, but its magnitude remains unknown. The influence of personal factors such as motivation complicates the interpretation of the results. Despite these drawbacks, the Sorensen test has become the tool of reference for evaluating muscle performance in patients with low back pain, most notably before and after rehabilitation programs.
Journal of applied physiology (Bethesda, Md. : 1985), 2003
Skeletal muscle voluntary contractions (VC) and electrical stimulations (ES) were compared in eig... more Skeletal muscle voluntary contractions (VC) and electrical stimulations (ES) were compared in eight healthy men. High-energy phosphates and myoglobin oxygenation were simultaneously monitored in the quadriceps by interleaved (1)H- and (31)P-NMR spectroscopy. For the VC protocol, subjects performed five or six bouts of 5 min with a workload increment of 10% of maximal voluntary torque (MVT) at each step. The ES protocol consisted of a 13-min exercise with a load corresponding to 10% MVT. For both protocols, exercise consisted of 6-s isometric contractions and 6-s rest cycles. For an identical mechanical level (10% MVT), ES induced larger changes than VC in the P(i)-to-phosphocreatine ratio [1.38 +/- 1.14 (ES) vs. 0.13 +/- 0.04 (VC)], pH [6.69 +/- 0.11 (ES) vs. 7.04 +/- 0.07 (VC)] and myoglobin desaturation [43 +/- 15.9 (ES) vs. 6.1 +/- 4.6% (VC)]. ES activated the muscle facing the NMR coil to a greater extent than did VCs when evaluated under identical technical conditions. This met...
The treatment of choice for tendinopathies is eccentric reeducation. Although the clinical result... more The treatment of choice for tendinopathies is eccentric reeducation. Although the clinical results appear favorable, the biomechanical changes to the tissue are not yet clear. Even if the mechanotransduction theory is commonly accepted, the physiology of tendons is not clearly understood. We aimed to better define the biomechanical and histological changes that affect healthy tendon after eccentric and concentric training. This study compared the effects of two methods of training (eccentric [E] training and concentric [C] training) with untrained (U) rats. The animals were trained over a period of 5 weeks. The tricipital, patellar, and Achilles tendons were removed, measured and a tensile test until failure was performed. A histological analysis (hematoxylin and eosin and Masson's trichrome stains) was also realized. There was a significant increase in the rupture force of the patellar and tricipital tendons between the U and E groups. The tricipital tendons in the control group presented a significantly smaller cross-sectional area than the E-and C-trained groups, but none was constated between E and C groups. No significant difference was observed for the mechanical stress between the three groups for all three tendons. Histological studies demonstrated the development of a greater number of blood vessels and a larger quantity of collagen in the E group. The mechanical properties of tendons in rats improve after specific training, especially following eccentric training. Our results partly explained how mechanical loading, especially in eccentric mode, could improve the healing of tendon. ß
The Journal of sports medicine and physical fitness, Jan 10, 2014
The aim of this study was to compare tennis players with and without low back pain (LBP) and heal... more The aim of this study was to compare tennis players with and without low back pain (LBP) and healthy sedentary participants regarding the trunk muscle strength and flexibility. Thirty--eight male elite tennis players and 22 healthy sedentary male students (24.8 ± 4.0 years) participated in this investigation. Tennis players were divided into two groups: 11 players (27.8 ± 5.5 years) with current LBP and 27 players (24.3 ± 5.9 years) without LBP. Maximal isometric strength of trunk extensor, rotator, flexor and lateralflexor muscles was assessed by means of specific trunk dynamometers. Pelvic and lumbar flexion mobility were measured by means of inclinometer technique. Comparison of tennis players with and without LBP revealed no significant difference regarding trunk muscle strength and ratio or lumbar spine flexibility (all p>0.05). In comparison with sedentary subjects, the tennis players showed a sport--specific profile determined by a non--dominant trunk lateralflexors (p=0.0...
Annales de réadaptation et de médecine physique : revue scientifique de la Société française de rééducation fonctionnelle de réadaptation et de médecine physique, 2007
The goals of this paper were to define the concept of instability, to describe the way it can be ... more The goals of this paper were to define the concept of instability, to describe the way it can be assessed, to report on impairments of the spine stabilization system in patients with low back pain (LBP), to cite the recommended exercises and, lastly, to examine the results of programs based on lumbar stabilization. Patients suffering from lumbar instability appear to belong to a particular subgroup of subjects with LBP. In the literature, several definitions of lumbar instability have been proposed. Radiological instability, for instance, differs from functional instability. Diagnosis remains difficult: the relevance of static and dynamic radiographs appears limited whereas several signs and clinical instability tests have been described in the literature but remain controversial. The functional stability system of the spine consists of three interdependent components: the passive, the active and the neuromuscular subsystems. The benefits of lumbar stabilization programs for LBP pat...
Electrical stimulation (ES) and voluntary contraction (VC) were compared in the quadriceps muscle... more Electrical stimulation (ES) and voluntary contraction (VC) were compared in the quadriceps muscle of ten male volunteers. In both modes, a workload corresponding to 20% of maximal voluntary contraction was applied during 64 isometric contraction (5.5 s)-relaxation (5.5 s) cycles. The protocols were performed in a 1.5 T whole-body magnet. The Pi/PCr ratio and the intracellular pH (pHi) were monitored by 31P NMR spectroscopy during baseline, exercise and recovery periods, in a superficial region of the vastus medialis. During baseline, the Pi/PCr ratio (0.12 vs. 0.10) and the pHi (7.01 vs. 7.00) were comparable in both conditions. During exercise, the Pi/PCr ratio was higher (0.36 vs. 0.14) and the pHi was lower (6.85 vs. 7.07) during ES than during VC. For the same external work production, these results reflect a different metabolic solicitation in the ES quadriceps than in the VC ones.
Introduction: Joint hypermobility involves an increased range of motion compared to normal amplit... more Introduction: Joint hypermobility involves an increased range of motion compared to normal amplitudes for the same age, sex and ethnic group. Patients with hypermobility suffer from joints problems and chronic pain is the most frequently reported symptom. Eccentric muscle strengthening could be very important to protect hypermobile joints.
The purpose of this study was to estimate the effects of intense and regular physical activity on... more The purpose of this study was to estimate the effects of intense and regular physical activity on locomotor system modifications. Tennis, with its unilateral solicitations, allows a more precise examination of specific localized development. Ten professional tennis players were compared with sedentary age-matched students. Muscular modifications were observed, mainly in the forearm circumference. The dominant side forearm circumference was 13% larger than the opposite side. Asymmetry was less in the upper arm and insignificant in the thorax and vertebra. Deep modifications in bone mineral content (BMC) were investigated by isotopic techniques, based on differential photon attenuation in bone and soft tissue of the forearm. Bone density was markedly increased in professional tennis players. Even in the nondominant side, radius BMC was 1.18 g HA/cm, 15% higher than in sedentary control students. The difference was yet larger in the dominant mid-radius, reaching 1.47 g HA/cm. The same differences were observed for the ulna and involved both cortical and trabecular bone. In the control group of sedentary students, no significant difference was noted between the two upper limbs. This study clearly demonstrates the positive correlation between exercise and bone mineralization. The precise mechanical constraints optimizing the favorable effect in the most efficient way should be studied.
The first test for evaluating the isometric endurance of trunk extensor muscles was described by ... more The first test for evaluating the isometric endurance of trunk extensor muscles was described by Hansen in 1964. In 1984, following a study by Biering-Sorensen, this test became known as the "Sorensen test" and gained considerable popularity as a tool reported to predict low back pain within the next year in males. The test consists in measuring the amount of time a person can hold the unsupported upper body in a horizontal prone position with the lower body fixed to the examining table. This test has been used in many studies, either in its original version or as variants. Although its discriminative validity, reproducibility, and safety seem good, debate continues to surround its ability to predict low back pain; in addition, the gender-related difference in position-holding time remains unexplained and the influence of body weight unclear. A contribution of the hip extensor muscles to position holding has been established, but its magnitude remains unknown. The influence of personal factors such as motivation complicates the interpretation of the results. Despite these drawbacks, the Sorensen test has become the tool of reference for evaluating muscle performance in patients with low back pain, most notably before and after rehabilitation programs.
Journal of applied physiology (Bethesda, Md. : 1985), 2003
Skeletal muscle voluntary contractions (VC) and electrical stimulations (ES) were compared in eig... more Skeletal muscle voluntary contractions (VC) and electrical stimulations (ES) were compared in eight healthy men. High-energy phosphates and myoglobin oxygenation were simultaneously monitored in the quadriceps by interleaved (1)H- and (31)P-NMR spectroscopy. For the VC protocol, subjects performed five or six bouts of 5 min with a workload increment of 10% of maximal voluntary torque (MVT) at each step. The ES protocol consisted of a 13-min exercise with a load corresponding to 10% MVT. For both protocols, exercise consisted of 6-s isometric contractions and 6-s rest cycles. For an identical mechanical level (10% MVT), ES induced larger changes than VC in the P(i)-to-phosphocreatine ratio [1.38 +/- 1.14 (ES) vs. 0.13 +/- 0.04 (VC)], pH [6.69 +/- 0.11 (ES) vs. 7.04 +/- 0.07 (VC)] and myoglobin desaturation [43 +/- 15.9 (ES) vs. 6.1 +/- 4.6% (VC)]. ES activated the muscle facing the NMR coil to a greater extent than did VCs when evaluated under identical technical conditions. This met...
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Papers by J. Crielaard