Effect of acute high-intensity interval exercise on a mouse model of doxorubicin-induced cardiotoxicity: a pilot study.

BACKGROUND: It is unknown whether high-intensity interval exercise (HIIE) may potentiate or attenuate the cardiotoxic effect of chemotherapy agents such as doxorubicin (DOX) when performed shortly after treatment. The study aimed to investigate the effect of acute HIIE on cardiac function and structure performed either 1, 2 or 3 days after DOX injection in an animal model. METHODS: Female C57bl/6 mice (n = 28), 70 days old, received a bolus 20 mg/kg intravenous tail vein DOX injection. Three exercise groups performed 1 HIIE session (16 sets of 1 min at 85-90% of peak running speed) at 1 (n = 7), 2 (n = 7), and 3 days (n = 8) following the DOX injection. A sedentary (SED) group of mice (n = 6) did not exercise. Animals underwent echocardiography under light anesthesia (isoflurane 0.5-1%) before and 7 days after the DOX injection. Animals were sacrificed on day 9 and hearts were collected for morphometric and histological analysis. RESULTS: Animals exercising on day 3 had the smallest pre-post reduction in left ventricular fractional shortening (LVFS) (MΔ= -1.7 ± 3.3; p = 0.406) and the SED group had the largest reduction (MΔ=-6.8 ± 7.5; p = 0.009). After reclassification of animals according to their exercise compliance (performing > 8/16 of high-intensity bouts), LVFS in compliant mice was unchanged over time (LVFS MΔ= -1.3 ± 5.6; p = 0.396) while non-compliant animals had a LVFS reduction similar to sedentary animals. There were no significant differences in myocardial histology between groups. CONCLUSIONS: In this pilot murine study, one single HIIE session did not exacerbate acute doxorubicin-induced cardiotoxicity. The timing of the HIIE session following DOX injection and the level of compliance to exercise could influence the negative impact of DOX on cardiac function.

Musculoskeletal symptoms in an adolescent athlete population: a comparative study.

BACKGROUND: Musculoskeletal pain, symptoms or injuries are prevalent in the adolescent athlete population as well as in the general adolescent population, and often have significant consequences on their future musculoskeletal health. However, differences between these two populations in regards to their musculoskeletal health are not known and have not yet been explored. Therefore, the main objectives of this study are to 1) compare the 6-month prevalence of musculoskeletal symptoms and their impact on school attendance and reduction in sport or leisure activity between a group of adolescent athletes and a group of control adolescents, and 2) determine if gender has different effects on the prevalence of musculoskeletal symptoms in these two populations. METHODS: Among adolescents who participated in the 2012 Québec summer games, 1,865 agreed to participate and constituted the adolescent athletes group (mean age:14.12 ± 1.22). An additional cohort of 707 adolescents from two schools was also recruited to form the comparison control group (mean age: 14.69 ± 1.38). Anthropometric data were collected, and the musculoskeletal 6-month prevalence of symptoms and their related impacts were assessed using the Teen Nordic Musculoskeletal Screening Questionnaire (TNMQ-S). Participants' characteristics as well as symptoms prevalence for the nine anatomical regions as well as their impact on school/work absence and reduction in physical/leisure activities were compared between athletes and control adolescents. RESULTS: When compared to athlete adolescents, significantly more controls had a positive 6-month prevalence of symptoms affecting the neck (48.8% vs 26.3%), upper back (41.3% vs 18.1%) and low back (45.4% vs 35.8%) when compared to athlete. Symptoms affecting the spine led to significantly more school absence and reduction in physical activity in the control group. Controls also showed higher prevalence of shoulder (37.1% vs 28.3%) and wrist/hand (23.8% vs 17.4%) symptoms, while athletes had a higher prevalence of elbow symptoms (8.7% vs 11.4%). CONCLUSION: Despite their higher risk of injuries related to high levels of competition or sport participation, adolescent athletes have fewer symptoms affecting the spine than "typical adolescents", and similar prevalence of symptoms affecting the body's extremities. Further investigations are necessary to understand the differences between athletes and non-athletes in regard to disability and long-term complications associated to musculoskeletal pain or symptoms.

Assessment of musculoskeletal symptoms and their impacts in the adolescent population: adaptation and validation of a questionnaire.

BACKGROUND: Valid and reliable instruments measuring musculoskeletal symptoms prevalence and their impacts in the adolescent population are scarce. The Extended Nordic Musculoskeletal Questionnaire (NMQ-E) is a reliable instrument that measures the prevalence, severity and impact of musculoskeletal symptoms. The purpose of this study was: (1) to develop a musculoskeletal symptom screening tool for younger populations derived from the NMQ-E and NMQ French versions and (2) to assess the validity and reliability of the adapted version of the instrument. METHODS: Based on the results of a translated (French) and adapted NMQ-E administered to 61 adolescents, a final 27-item dichotomous questionnaire was developed. The questionnaire measured the 6-month prevalence of musculoskeletal symptoms and the impact of these symptoms on school attendance as well as on sports and leisure activity participation. Among the adolescents who agreed to participate, thirty-nine (mean age: 13.7 ± 1.8) formed the reliability cohort and thirty-four (mean age: 14.2 ± 2.3) formed the criterion validity cohort. Reliability was measured by test-retest with a mean time interval of 28 hours. Criterion validity was assessed by comparing the answers to the questionnaires to the participants' clinical records. Statistical tests used were proportions of observed agreement (Po) and the Cohen kappa statistic (k). RESULTS: The mean Po for the test-retest was 0.92 for the 6-month symptom prevalence items, 0.99 for the impact of symptoms on school items and 0.96 for the impact on sports and leisure activities items. Kappa values for the reliability assessment ranged between 0.57 and 1.00 for the 27 dichotomous variables. The criterion validity kappa obtained for the agreement between participants' clinical records and questionnaires was k = 0.76. CONCLUSIONS: Kappa values for the reliability and the criterion validity are of moderate to perfect agreement beyond chance, indicating that there are only minor variations between tests, and good agreement between questionnaire items and clinical records. These results indicate that the adapted version of the NMQ-E is an appropriate self-administered musculoskeletal symptom screening tool for the adolescent population. Items related to the impacts of symptoms would benefit from additional validation using school and sport attendance records.