In horses, it has been reported that strenuous, long-duration exercise triggers a systemic pro-inflammatory response similar to the events that occur during sepsis, with increased levels of circulating cytokines IL-6 (120-fold), TNF-α (3-fold) and IL-1β (4-fold) [ 16].
In 462 middle-aged Finnish men, ponderal index at birth was not associated with the duration of strenuous leisure time physical activity [4].
Conversely, Poh and colleagues reported that strenuous exercise of short duration, resulted in augmented E′RV as compared to baseline [ 26].
Because the duration of strenuous physical activity was reported in hours not in minutes, we chose a cut-off point (≥3 h per week) to dichotomize women into two groups.
As a consequence patients have to avoid strenuous activities and sports for the duration of the healing process, which might be years [ 6, 16].
Initial inclusion criteria included the ability to stay at home, abstain from strenuous physical activity for the study duration (4 d), access the Internet and live within a maximum of 30 min from the investigating centre.
Therefore, the speed and duration of even the most strenuous treadmill exercise protocol used here (up to 4 h of exercise daily) was not detrimental to the knee joint cartilage in these animals.
The LSI is a 3-item measure assessing the frequency and duration of mild, moderate and strenuous bouts of exercise performed during free time in a typical week.
Participants were asked over the 14 days prior the questionnaire, how many days they had participated in strenuous activity for at least 20 minutes duration.
The LSI is a 3-item measure assessing the frequency and duration of mild, moderate and strenuous bouts of physical activity performed during free time in a typical week.
