Juha E. Peltonen

Stability of leisure-time physical activity during adolescence - a longitudinal study among 16-, 17- and 18-year-old Finnish youth

Participation in physical activity during childhood and adolescence is frequently mentioned as one factor likely to promote a more active lifestyle in adulthood with its health benefits. We studied the changes in leisure‐time physical activity pattern and self‐reported fitness during a three‐year period in adolescence and investigated whether the type of sports has an effect on stability of physical activity at leisure. A questionnaire with identical physical activity items was sent to Finnish twins on their 16th and 17th birthdays and 6 months after the 18th birthday. A total of 1338 boys and 1596 girls responded to all three questionnaires, with response rates of 73.6% and 86.5%. The proportions of very active adolescents and adolescents with very good self‐reported fitness seem to be alike at each age. Among girls, 23.7% to 27.7% reported being very active (4–5 times a week) and 13.7% to 15.1% considered their physical fitness to be very good at the ages of 16, 17 and 18. Among boys, the comparable percentages were 31.5% to 35.5% and 30.6% to 34.4%. However, the longitudinal three‐year follow up showed substantial changes over time among individuals from one physical activity group to another. Only 19.1% of boys and 11.2% of girls were persistent exercisers (i.e., very active on all three years) and 15.6% of boys and 5.1% of girls were persistently fit (i.e., very good self‐reported fitness on all three years). Stability of leisure‐time physical activity was highest among those who participated in several different types of sports. Among boys the proportion of persistent exercisers was highest for those who participated in cross‐country skiing, jogging and body‐building (22.0–41.5%) and among girls for those who participated in ball games (11.9–28.6%). Those who participated in organised sports were more often persistent exercisers than those who did not (odds ratio = 13.2 for boys (CI 9.4–18.7) and 8.9 for girls (CI 6.4–12.5)). Also, those who participated in organised sports were more often persistently fit (odds ratio = 7.3 for boys (CI 5.2–10.2) and 10.4 for girls (CI 6.4–16.9). Adolescents are recommended to participate in and try different types of sports, and especially for girls ball games would appear to favour long‐term maintenance of leisure‐time physical activity.

Back extensor and psoas muscle cross-sectional area, prior physical training, and trunk muscle strength : a longitudinal study in adolescent girls

Abstract The association between physical training, low back extensor (erector spinae plus multifidus muscles) and psoas muscle cross-sectional areas (CSA) and strength characteristics of trunk extension and flexion were studied in adolescent girls. A group of athletes (n=49) (age range 13.7–16.3 years) consisting of gymnasts, figure skaters and ballet dancers was age-matched with non-athletes (n=17) who acted as a sedentary control group. The CSA of psoas muscles and multifidus plus erector spinae muscles were measured from lumbar axial images by magnetic resonance imaging. Maximal trunk extension and flexion forces were measured in a standing position using a dynamometer and trunk musculature endurance was evaluated using static holding tests. When CSA were adjusted with body mass, the athletes showed significantly greater CSA in both muscles studied (psoas P < 0.001; erector spinae plus multifidus P < 0.05) than the non-athletes. The athletes also had a greater absolute psoas muscle CSA (P < 0.01) and trunk flexion force (P < 0.01) compared to the controls. When the forces were expressed relative to body mass, the athletes were superior both in trunk flexion (P < 0.001) and extension (P < 0.001). There was a significant correlation between muscle CSA and strength parameters, but the force per muscle CSA did not differ significantly between the athletes and the non-athletes. In addition, the athletes showed a better body mass adjusted muscle endurance in trunk flexion (P < 0.05) than the non-athletes. Our study indicated that regular physical training enhances trunk musculature hypertrophy, force and endurance in adolescent girls, and that there is an association between muscle CSA and strength parameters.

Effects of oxygen fraction in inspired air on rowing performance.

The present study examined the effect of oxygen fraction in inspired air (FIO2) on exercise performance and maximum oxygen consumption (VO2max). Six national level male rowers exercised three 2500-m all-out tests on a Concept II rowing ergometer. Each subject performed one test in normoxia (FIO2 20.9%), one in simulated hyperoxia (FIO2 62.2%) and one in simulated hypoxia (FIO2 15.8%) in a randomized single-blind fashion. The mean final rowing time was 2.3 +/- 0.9% (P < 0.01; 95% CI 1.4-3.2) shorter in hyperoxia and 5.3 +/- 1.8% (P < 0.01; 95% CI 3.1-7.5) longer in hypoxia when compared with normoxia. The effect of FIO2 on VO2max exceeded its effect on exercise performance as VO2max was 11.1 +/- 5.7% greater (P < 0.01; 95% CI 5.1-17.1) in hyperoxia and 15.5 +/- 3.2% smaller in hypoxia (P < 0.01; 95% CI 12.2-19.0) than in normoxia. Blood lactate concentration and O2 consumption per power unit (ml O2.W-1) failed to indicate statistically significant differences in anaerobic metabolism between normoxia and the other two conditions. These data suggest that there are other parameters besides those of energy metabolism that affect exercise performance as FIO2 is modified. These possible mechanisms are discussed in this paper.

Life events and change in leisure time physical activity: a systematic review.

The global epidemic of chronic non-communicable diseases is closely related to changes in lifestyle, including decreasing leisure time physical activity (PA). Physical inactivity is a major public health challenge. To respond to that challenge, it is essential to know which personal and environmental factors affect PA behaviour. Certain life events may be one contributing factor, by creating emotional distress and disrupting a person’s daily routine.The aim was to examine the literature concerning the effects of life events on changes in PA. A systematic literature search was performed on studies that assessed at least one major change in life circumstances and a change in PA. To be included, studies had to assess PA at two timepoints at least (before and after the event). Diseases as life events were excluded from this review. Thirty-four articles met the inclusion criteria. The studies examined the following life-change events: transition to university; change in employment status; marital transitions and changes in relationships; pregnancy/having a child; experiencing harassment at work, violence or disaster; and moving into an institution.The studies reviewed showed statistically significant changes in leisure PA associated with certain life events. In men and women, transition to university, having a child, remarriage and mass urban disaster decreased PA levels, while retirement increased PA. In young women, beginning work, changing work conditions, changing from being single to cohabiting, getting married, pregnancy, divorce/separation and reduced income decreased PA. In contrast, starting a new personal relationship, returning to study and harassment at work increased PA. In middle-aged women, changing work conditions, reduced income, personal achievement and death of a spouse/partner increased PA, while experiencing violence and a family member being arrested or jailed decreased PA. In older women, moving into an institution and interpersonal loss decreased PA, while longer-term widowhood increased PA. In addition, experiencing multiple simultaneous life events decreased PA in men and women.Major life events have a strong effect on leisure PA behaviour. Consequently, people experiencing life events could be an important target group for PA promotion. More research is needed to examine the short- and longterm effects of different life events on PA, gender differences in the effects of life events and the specific determinants of PA change during life events.

Prediction of Acute Mountain Sickness by Monitoring Arterial Oxygen Saturation During Ascent

Acute mountain sickness (AMS) is a common problem while ascending at high altitude. AMS may progress rapidly to fatal results if the acclimatization process fails or symptoms are neglected and the ascent continues. Extensively reduced arterial oxygen saturation at rest (R-Spo₂) has been proposed as an indicator of inadequate acclimatization and impending AMS. We hypothesized that climbers less likely to develop AMS on further ascent would have higher Spo₂ immediately after exercise (Ex-Spo₂) at high altitudes than their counterparts and that these postexercise measurements would provide additional value for resting measurements to plan safe ascent. The study was conducted during eight expeditions with 83 ascents. We measured R-Spo₂ and Ex-Spo₂ after moderate daily exercise [50 m walking, target heart rate (HR) 150 bpm] at altitudes of 2400 to 5300 m during ascent. The Lake Louise Questionnaire was used in the diagnosis of AMS. Ex-Spo₂ was lower at all altitudes among those climbers suffering from AMS during the expeditions than among those climbers who did not get AMS at any altitude during the expeditions. Reduced R-Spo₂ and Ex-Spo₂ measured at altitudes of 3500 and 4300 m seem to predict impending AMS at altitudes of 4300 m (p < 0.05 and p < 0.01) and 5300 m (both p < 0.01). Elevated resting HR did not predict impending AMS at these altitudes. Better aerobic capacity, younger age, and higher body mass index (BMI) were also associated with AMS (all p < 0.01). In conclusion, those climbers who successfully maintain their oxygen saturation at rest, especially during exercise, most likely do not develop AMS. The results suggest that daily evaluation of Spo₂ during ascent both at rest and during exercise can help to identify a population that does well at altitude.

Effects of oxygen fraction in inspired air on force production and electromyogram activity during ergometer rowing.

Abstract Six male rowers rowed maximally for 2500 m in ergometer tests during normoxia (fractional concentration of oxygen in inspired air, FIO2 0.209), in hyperoxia (FIO2 0.622) and in hypoxia (FIO2 0.158) in a randomized single-blind fashion. Oxygen consumption (V˙O2), force production of strokes as well as integrated electromyographs (iEMG) and mean power frequency (MPF) from seven muscles were measured in 500-m intervals. The iEMG signals from individual muscles were summed to represent overall electrical activity of these muscles (sum-iEMG). Maximal force of a stroke (Fmax) decreased from the 100% pre-exercise maximal value to 67 (SD 12)%, 63 (SD 15)% and 76 (SD 13)% (P<0.05 to normoxia, ANOVA) and impulse to 78 (SD 4)%, 75 (SD 14)% and 84 (SD 7)% (P<0.05) in normoxia, hypoxia and hyperoxia, respectively. A strong correlation between Fmax and V˙O2 was found in normoxia but not in hypoxia and hyperoxia. The mean sum-iEMG tended to be lower (P<0.05) in hypoxia than in normoxia but hyperoxia had no significant effect on it. In general, FIO2 did not affect MPF of individual muscles. In conclusion, it was found that force output during ergometer rowing was impaired during hypoxia and improved during hyperoxia when compared with normoxia. Moreover, the changes in force output were only partly accompanied by changes in muscle electrical activity as sum-iEMG was affected by hypoxic but not by hyperoxic gas. The lack of a significant correlation between Fmax and V˙O2 during hypoxia and hyperoxia may suggest a partial uncoupling of these processes and the existence of other limiting factors in addition to V˙O2.

Prevalence of Acute Mountain Sickness among Finnish Trekkers on Mount Kilimanjaro, Tanzania: An Observational Study

The aim of this study was to evaluate the prevalence of acute mountain sickness (AMS) among trekkers on Mount Kilimanjaro during the winter season of 2006-2007. A A total of 130 Finnish trekkers at Marungu route were asked to complete daily a Lake Louise self-report and clinical assessment score questionnaire with the help of a trainee Finnish guide during their trek to Kilimanjaro. A Lake Louise questionnaire score>or=3 indicated AMS. Altogether 112 mountaineers or travelers [54 men, 58 women, mean age 51+/-10 (SD) years] were studied. Fifty-nine travelers (53%) reached Gillmans Point or Uhuru Peak. The incidence of AMS among Finnish Kilimanjaro trekkers was 75%. The most common high altitude symptoms were headache, followed by sleeping problems and fatigue or weakness. The incidence of AMS is high among trekkers climbing Mount Kilimanjaro.The main reason for this seems to be rapid ascent. Kilimanjaro treks normally have a fixed timetable, and for commercial reasons there is little opportunity to spend extra days for acclimatization in the camps. Some contributing factors are preventable, so we recommend an educational program for all the trekking agencies that guide on this peak and, in particular, the Tanzania-based guiding agencies, which, typically, are driving these very fast ascent rates.

Cerebral and muscle tissue oxygenation in acute hypoxic ventilatory response test

Eight men were exposed to progressive isocapnic hypoxia for 10 min to test the hypothesis that (i) cerebral and muscle tissue would follow similar deoxygenation profiles during an acute hypoxic ventilatory response (AHVR) test; and (ii) strong cerebrovascular responsiveness to hypoxia would be related to attenuated cerebral deoxygenation. End-tidal O(2) concentration was reduced from normoxia (approximately 102 mmHg) to approximately 45 mmHg while arterial oxygen saturation (SpO2 %) declined from 98+/-1% to 77+/-7% (P<0.001). Near-infrared spectroscopy (NIRS)-derived local cerebral tissue (frontal lobe) deoxyhemoglobin increased 5.55+/-2.22 microM, while oxyhemoglobin and tissue oxygenation index decreased 2.57+/-1.99 microM and 6.2+/-3.4%, respectively (all P<0.001). In muscle (m. vastus lateralis) the NIRS changes from the initial normoxic level were non-significant. Cerebral blood velocity (V(mean), transcranial Doppler) in the middle cerebral artery increased from 53.4+/-10.4 to 60.6+/-11.6 cms(-1) (P<0.001). In relation to the decline in SpO2 % the mean rate of increase of V(mean) and AHVR were 0.33+/-0.19 cms(-1)%(-1) and 0.52+/-0.20l min(-1)%(-1), respectively. We conclude that cerebral, but not muscle, tissue shows changes reflecting a greater deoxygenation during acute hypoxia. However, the changes in NIRS parameters were not related to cerebrovascular responsiveness or ventilatory chemosensitivity during graded hypoxia.

Cerebral and muscle deoxygenation, hypoxic ventilatory chemosensitivity and cerebrovascular responsiveness during incremental exercise.

To examine if cerebral (frontal cortex) and skeletal muscle (m. vastus lateralis) deoxygenation and cerebral blood flow velocity (V(mean)) in the middle cerebral artery differentiated between normoxic and hypoxic (end-tidal P(O)(2) 71 mmHg) conditions, and if they were associated with hypoxic ventilatory chemosensitivity and cerebrovascular responsiveness, 8 men performed incremental cycling trials (30W/min ramp) under normoxic (T1-N) and hypoxic (T1-H) conditions until volitional fatigue, or until arterial O2 saturation decreased below 80%. The tests were repeated (T2-N; T2-H) on another day with supplemental O2 (Sup-O2) at the end of exercise. The V(mean) response was similar in normoxia and hypoxia. In hypoxia compared to normoxia, cerebral deoxygenation ( upward arrow deoxyhemoglobin concentration (Delta[HHb]) and downward arrow tissue oxygenation index (TOI)) was greater at a given work rate. A strong hypoxic ventilatory chemosensitivity was associated with a rapid reduction of cerebral TOI (r=0.94, P<0.001). Muscle deoxygenation was similar in normoxia and hypoxia suggesting greater muscle blood flow in hypoxia compared to normoxia and thus the existence of control features that match muscle perfusion and O2 delivery tightly with O2 demand during exercise. Sup-O2 reduced both cerebral and muscle deoxygenation, at least transiently.

Back to the Future: Proceedings From the 2010 NF Conference

The neurofibromatoses (NF) encompass the rare diseases NF1, NF2, and schwannomatosis. The NFs affect 100,000 Americans; over 2 million persons worldwide; and are caused by mutation of tumor suppressor genes. Individuals with NF1 in particular may develop tumors anywhere in the nervous system; additional manifestations can include learning disabilities, bone dysplasia, cardiovascular defects, unmanageable pain, and physical disfigurement. Ultimately, the NFs can cause blindness, deafness, severe morbidity, and increased mortality and NF1 includes a risk of malignant cancer. Today there is no treatment for the NFs (other than symptomatic); however, research efforts to understand these genetic conditions have made tremendous strides in the past few years. Progress is being made on all fronts, from discovery studies—understanding the molecular signaling deficits that cause the manifestations of NF—to the growth of preclinical drug screening initiatives and the emergence of a number of clinical trials. An important element in fuelling this progress is the sharing of knowledge, and to this end, for over 20 years the Childrens Tumor Foundation has convened an annual NF Conference, bringing together NF professionals to share ideas and build collaborations. The 2010 NF Conference held in Baltimore, MD June 5–8, 2010 hosted over 300 NF researchers and clinicians. This paper provides a synthesis of the highlights presented at the Conference and as such, is a “state‐of‐the‐field” for NF research in 2010.