television-watching have been shown to relate to spinal pain in some studies (2,5) but not others (1,10). Again, it seems that this mismatch may relate to the definitions of back pain, with only the studies recognising milder pain showing an effect. Again, these are snapshot studies, and so advising a reduction of television-watching is not supported fully by the evidence. Nevertheless, as posture is likely to mediate any effect on spinal pain, the posture advice described earlier may be useful.

OTHER SPECIFIC SEDENTARY ACTIVITIES Reading books and magazines does not seem to involve the adoption of risky postures in adolescents (11), and in accordance with this another study has shown no associations between reading and spinal pain (5). However, a more recent study has shown that girls who read a lot get more neck pain (2). This was not seen in boys and seems to tally with findings from an older study by Niemi and colleagues, which also showed effects in girls but not in boys (12). Niemi and colleagues showed that neck pain was more likely in girls who engaged most in static upper- limb activities (eg. reading, playing musical instruments, needlework) than in girls who participated in dynamic upper- limb activities (eg. racquet sports). This gender difference is typical of many risk factors for spinal pain and probably relates to the very different specific activities actually undertaken and to differences in the way the activities are performed. Interestingly, the difference in effects of static and dynamic activities in the girls was attributed to static activities increasing upper spine muscle tension and dynamic activities decreasing it, and so it may be that the female adolescents tended to develop more upper body tension than the boys. Auvinen and

EXPLAIN THE GROWTH IN ADOLESCENT SPINAL PAIN OVER THE PAST 15 YEARS

colleagues found that sitting for more than 4 hours after school was associated with higher rates of neck pain in adolescents, although this sitting time included computer use and watching television, so it is unclear whether it was the sitting itself or the activities undertaken during sitting that were important (2). Despite the limitations of these studies, they do suggest that advice to take active breaks during sedentary activities, where the focus is on dissipating any muscle tension, may be helpful.

LOW OVERALL ACTIVITY LEVELS So far we have looked at specific types of sedentary activity. What about the effects of being sedentary per se? In other words, does a mere lack of strenuous activity associate with spinal pain? Low activity might increase spinal pain by reducing local muscle endurance and thus decreasing spinal stability. Vikat and colleagues measured overall levels of activity and found that adolescents with the lowest activity levels overall were at a higher risk of both neck and back pain than those with average activity levels (13). Their findings could result from the mere lack of activity, but they could also be due to the low activity levels resulting from a higher participation in risky activities such as computer use. Unfortunately, this will never be known, as they did not measure the amount of computer use or similar activities. In a longitudinal study, Salminen and colleagues did not observe any effect of low activity levels on the onset of spinal pain 3 years later, but the small sample size may have contributed to this inconclusive finding (14). Further work is needed before low activity levels per se can be implicated. It is important to realise that engaging in lots of sedentary activities does not necessarily mean that an adolescent is sedentary overall. The tendency is to assume that such sedentary activities may reduce overall activity levels through reducing the leisure time available, but this is not always the case, as there is evidence that some gamers also tend to compensate by engaging in vigorous physical activities as well (15). A typical group are male, white and from a privileged socioeconomic group, who participate in a high level of gaming and a lot of skateboarding or skating (15).

HIGHER ACTIVITY LEVELS What about more strenuous physical activities? How do they relate to back pain? Despite the established relationships between higher activity and

better general physical and mental health, there is some evidence that the highest levels of activity in adolescents may be related to more spinal pain. In a very recent Finnish study of nearly 6,000 adolescents, Auvinen and colleagues showed that high levels of physical activity were associated with neck pain in girls, although surprisingly not in boys (2). Similarly Vikat and colleagues demonstrated that the risks of

14 sportEX medicine 2009;41(Jul):12-19

THE GROWING USE OF INFORMATION TECHNOLOGY MIGHT