Jaap Jansen
Utrecht University
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Featured researches published by Jaap Jansen.
Manual Therapy | 2011
A Weir; Jaap Jansen; I.G.L. van de Port; H.B.A. Van de Sande; Johannes L. Tol; Frank J.G. Backx
HYPOTHESIS A multi-modal treatment program (MMT) is more effective than exercise therapy (ET) for the treatment of long-standing adductor-related groin pain. STUDY DESIGN Single blinded, prospective, randomised controlled trial. METHODS PATIENTS Athletes with pain at the proximal insertion of the adductor muscles on palpation and resisted adduction for at least two months. INTERVENTIONS ET: a home-based ET and a structured return to running program with instruction on three occasions from a sports physical therapist. MMT: Heat, Van den Akker manual therapy followed by stretching and a return to running program. PRIMARY OUTCOME time to return to full sports participation. SECONDARY OUTCOME MEASURES objective outcome score and the visual analogue pain score during sports activities. Outcome was assessed at 0, 6, 16 and 24 weeks. RESULTS Athletes who received MMT returned to sports quicker (12.8 weeks, SD 6.0) than athletes in the ET group (17.3 weeks, SD 4.4. p = 0.043). Only 50-55% of athletes in both groups made a full return to sports. There was no difference between the groups in objective outcome (p = 0.72) or VAS during sports (p = 0.12). CONCLUSIONS The multi-modal program resulted in a significantly quicker return to sports than ET plus return to running but neither treatment was very effective.
Antiviral Research | 1983
Cornelis A. Kraaijeveld; Geertje la Rivière; Barry Benaissa-Trouw; Jaap Jansen; Theo Harmsen; Harm Snippe
The effects of the adjuvant dimethyl dioctadecyl ammonium bromide (DDA) on the immune responses to encephalomyocarditis (EMC) virus were studied in mice. The humoral response, as measured by appearance of neutralizing antibodies, was slightly enhanced in mice immunized by the intraperitoneal route. Intracutaneously, DDA almost did not affect the humoral response but resulted in distinct enhancement of delayed type hypersensitivity (DH), as measured by the footpad swelling test. DH to EMC virus was found to be antigen-specific and could be passively transferred to normal mice with peritoneal exudate cells from immunized mice. Dose-response curves for DH and humoral antibody responses to EMC virus were not concordant. Low doses induced DH on day 6 without measurable circulating antibodies; high doses gave good antibody responses but suboptimal DH reactions. Immunization conferred a state of resistance to infection with virulent EMC virus. Protection seemed more related to DH than to the prevalence of specific antibodies at the time of infection.
Manual Therapy | 2010
Jaap Jansen; A Weir; Renee Dénis; Jan Mens; Frank J.G. Backx; Henk J. Stam
The purpose of the study was to compare thickness of the transversus abdominis (TA) and obliquus internus (OI) muscles between athletes with and without longstanding adduction-related groin pain (LAGP). Forty two athletes with LAGP and 23 controls were included. Thickness of TA and OI were measured with ultrasound imaging on the right side of the body during rest. Relative muscle thickness (compared to rest) was measured during the active straight leg raise (ASLR) left and right, and during isometric hip adduction. TA resting thickness was significantly smaller in injured subjects with left-sided (4.0+/-0.82mm; P<0.001) or right-sided (4.3+/-0.64mm; P=0.015) groin complaints compared with controls (4.9+/-0.90mm). No significant differences between patients and controls in TA or OI relative thickness during the ASLR and isometric hip adduction were found (all cases P>/=0.15). In conclusion, TA resting thickness is smaller in athletes with LAGP and may thus be a risk factor for (recurrent) groin injury. This may have implications for therapy and prevention of LAGP.
Physical Therapy in Sport | 2010
A Weir; Jaap Jansen; Joyce van Keulen; Jan Mens; Frank J.G. Backx; Henk J. Stam
OBJECTIVE To evaluate short and mid-term results of active physical therapy in athletes with longstanding groin pain. DESIGN Case series. SETTING Primary care physical therapy practice. PARTICIPANTS A total of 44 athletes suffering longstanding adductor-related groin pain. INTERVENTION A combination of passive (joint mobilization) and active (exercises) physical therapy interventions. MAIN OUTCOME MEASUREMENTS Return to (the same level of) sports, restriction in sports, and recurrence. RESULTS Directly after treatment, return to the same level and type of sport was successful in 38 athletes (86%), and without symptoms in 34 athletes (77%). At 6.5-51 months follow up, 10/38 (26%) of those that returned to sports had experienced a relapse; 22 (50%) athletes were able to participate in sports without any restrictions at the mid-term follow-up. CONCLUSIONS For athletes with longstanding groin pain, short term results of physical therapy seem positive, whereas mid-term results are moderately positive. The risk for recurrence is high.
Journal of Orthopaedic & Sports Physical Therapy | 2009
Jaap Jansen; Jan Mens; Frank J.G. Backx; Henk J. Stam
STUDY DESIGN Longitudinal single-cohort study. BACKGROUND Athletes with longstanding groin pain associated with resisted hip adduction have been shown to have abnormal activation of the transversus abdominis (TA). Therefore, exercises targeting the TA to help stabilize the lumbopelvic area are generally used in the rehabilitation of these athletes. OBJECTIVES To investigate if (1) changes in abdominal muscle resting thickness and changes in relative thickness during lower extremity tasks after 14 weeks of intervention are related to changes in clinical status and (2) the changes in abdominal muscle resting/relative thickness are significant postintervention. METHODS In 21 athletes with longstanding groin pain associated with resisted hip adduction, ultrasound imaging of the abdominal musculature on the right side was performed at rest, during the active straight-leg raise (left and right), and during bilateral isometric hip adduction. Athletes then followed a 14-week rehabilitation protocol. Clinical outcome measured by self-reported sports restriction and change in abdominal muscle resting and relative thickness during lower extremity tasks were evaluated. RESULTS There was an overall significant decrease in self-reported sports restriction after intervention for this group of athletes. Apart from a significant negative correlation for changes in TA resting thickness, no significant association between changes in abdominal muscle thickness and change in self-reported sports restriction were found. Postintervention, TA resting thickness was significantly increased but relative thickness during the lower extremity tasks was found not to be statistically different for all muscles, except for a decreased relative thickness of obliquus externus abdominus (OE) during the active straight-leg raise for the left lower extremity. CONCLUSION There was no association between changes in abdominal muscle resting thickness and relative thickness during lower extremity tasks, and change in self-reported sports restriction after a period of physical therapy in athletes with longstanding groin pain associated with resisted hip adduction. Although this study was designed as a single-cohort longitudinal study, the data suggest that the intervention described can change TA resting thickness. The intervention did not influence abdominal muscle relative thickness during lower extremity tasks.
Research Quarterly for Exercise and Sport | 2014
Jeannette A. C. Lankhaar; Wouter R. de Vries; Jaap Jansen; Pierre Zelissen; Frank J.G. Backx
Purpose: This systematic review describes the state of the art of the impact of hypothyroidism on exercise tolerance and physical performance capacity in untreated and treated patients with hypothyroidism. Method: A systematic computer-aided search was conducted using biomedical databases. Relevant studies in English, German, and Dutch, published from the earliest date of each database up to December 2012, were identified. Results: Out of 116 studies, a total of 38 studies with 1,379 patients fulfilled the inclusion criteria. These studies emphasize the multifactorial causes of exercise intolerance in untreated patients by the impact of limitations in different functional systems, with cardiovascular, cardiopulmonary, musculoskeletal, neuromuscular, and cellular metabolic systems acting in concert. Moreover, the studies affirm that exercise intolerance in patients is not always reversible during adequate hormone replacement therapy. As a consequence, despite a defined euthyroid status, there remains a significant group of treated patients with persistent complaints related to exercise intolerance who are suffering from limitations in daily and sport activities, as well as an impaired quality of life. An explanation for this phenomenon is lacking. Only 2 studies investigated the effects of a physical training program, and they showed inconsistent effects on the performance capacity in untreated patients with subclinical hypothyroidism. Conclusions: A limited body of knowledge exists concerning exercise tolerance in treated patients with hypothyroidism, and there is an insufficient amount of quantitative studies on the effects of a physical training program. To enhance exercise and sports participation for this specific group, more research in this forgotten area is warranted.
The Clinical Journal of Pain | 2010
Jaap Jansen; Bart Poot; Jan Mens; Frank J.G. Backx; Henk J. Stam
ObjectivesIt is not clear whether abnormal abdominal muscle behavior in athletes with longstanding groin pain is a risk factor for groin pain or is caused by groin pain itself. Therefore, this study investigated whether anticipation of experimental groin pain influences abdominal muscle behavior. MethodsIn 14 healthy athletes, abdominal muscle thickness was measured using ultrasound under conditions of anticipated groin pain and acute groin pain. Groin pain was induced using superficial electrical skin stimulation. Tasks evaluated were isometric hip adduction and active straight leg raise (ASLR) left. ResultsThe m. transversus abdominis and m. obliquus internus showed a significant decrease in thickness during “anticipation of pain” compared with “no pain” and “pain” during both hip adduction and ASLR (P values <0.04). For m. obliquus externus, a significant increase in thickness was found only during “pain” compared with “no pain” and “anticipation of pain” for ASLR (P<0.004). DiscussionIf ASLR or hip adduction is associated with anticipated groin pain, abdominal muscle behavior is different from a pain-free situation and from a painful situation. These results suggest that abnormal abdominal muscle behavior found in athletes with longstanding groin pain may be caused by a pain anticipatory motor strategy. This may have implications for rehabilitation.
Clinical Journal of Sport Medicine | 2010
Jaap Jansen; Jan Mens; Frank J.G. Backx; Henk J. Stam
Objective:To investigate whether abdominal muscle thickness in athletes with long-standing adduction-related groin pain (LAGP) differs between subgroups with a positive or no response to a pelvic belt. The response to a pelvic belt is defined positive in case of a decrease ≥1 on a Likert pain scale (0-10) during the squeeze test (SQT) or a decrease ≥1 on the active straight leg raise (ASLR) test score (0-10). Design:Cross-sectional study. Setting:Physical therapy practice. Patients:Fifty athletes with LAGP. Independent Variables:Squeeze test and ASLR test. Main Outcome Measures:First, the effect of a pelvic belt on pain during the SQT and the ASLR test score was evaluated. Then, thickness of m. transversus abdominis (TA) and m. obliquus internus (OI) was measured using ultrasound during rest, ASLR left and right, and SQT. Results:Of the 50 participants, 25 (50%) experienced a decrease in pain during the SQT when wearing a pelvic belt and 10 (20%) improved in ASLR performance with a pelvic belt. Thickness of TA and OI at rest (both cases P > .08) and relative thickness compared with rest during tasks (in all cases P > .12) revealed no significant difference when comparing the 2 subgroups based on the belt response during the SQT or ASLR. Conclusions:Using these methods, abdominal muscle thickness behavior in athletes with LAGP did not differ between the subgroups based on a positive or no response to a pelvic belt. However, the ultrasound method used may not have been sensitive enough to reveal differences between groups.
Archives of Virology | 1983
Cornelis A. Kraaijeveld; Jaap Jansen; Barry Benaissa-Trouw; Harm Snippe
SummaryAfter subcutaneous infection of mice with Semliki Forest virus, a delayed-type hypersensitivity (DH) could be demonstrated by footpad swelling. Pretreatment with cyclophosphamide resulted in enhanced DH if neutralizing antibodies were undetectable in serum.
Physical Therapy in Sport | 2011
A Weir; Jaap Jansen; Joyce van Keulen; Jan Mens; Frank J.G. Backx; Henk J. Stam