3-year follow-up results of bone mineral content and density after a school-based physical activity randomized intervention trial.

BACKGROUND: As an important modifiable lifestyle factor in osteoporosis prevention, physical activity has been shown to positively influence bone mass accrual during growth. We have previously shown that a nine month general school based physical activity intervention increased bone mineral content (BMC) and density (aBMD) in primary school children. From a public health perspective, a major key issue is whether these effects persist during adolescence. We therefore measured BMC and aBMD three years after cessation of the intervention to investigate whether the beneficial short-term effects persisted. METHODS: All children from 28 randomly selected first and fifth grade classes (intervention group (INT): 16 classes, n=297; control group (CON): 12 classes, n=205) who had participated in KISS (Kinder-und Jugendsportstudie) were contacted three years after cessation of the intervention program. The intervention included daily physical education with daily impact loading activities over nine months. Measurements included anthropometry, vigorous physical activity (VPA) by accelerometers, and BMC/aBMD for total body, femoral neck, total hip, and lumbar spine by dual-energy X-ray absorptiometry (DXA). Sex- and age-adjusted Z-scores of BMC or aBMD at follow-up were regressed on intervention (1 vs. 0), the respective Z-score at baseline, gender, follow-up height and weight, pubertal stage at follow-up, previous and current VPA, adjusting for clustering within schools. RESULTS: 377 of 502 (75%) children participated in baseline DXA measurements and of those, 214 (57%) participated to follow-up. At follow-up INT showed significantly higher Z-scores of BMC at total body (adjusted group difference: 0.157 units (0.031-0.283); p=0.015), femoral neck (0.205 (0.007-0.402); p=0.042) and at total hip (0.195 (0.036 to 0.353); p=0.016) and higher Z-scores of aBMD for total body (0.167 (0.016 to 0.317); p=0.030) compared to CON, representing 6-8% higher values for children in the INT. No differences could be found for the remaining bone parameters. For the subpopulation with baseline VPA (n=163), effect sizes became stronger after baseline VPA adjustment. After adjustment for baseline and current VPA (n=101), intervention effects were no longer significant, while effect sizes remained the same as without adjustment for VPA. CONCLUSION: Beneficial effects on BMC of a nine month general physical activity intervention appeared to persist over three years. Part of the maintained effects may be explained by current physical activity.

Association of ECG abnormalities and incident heart failure events

Background: With the aging of the population, the heart failure (HF) incidence and prevalence trends are expected to significantly worsen unless concentrated prevention efforts are undertaken. ECG abnormalities are common in the elderly but data are limited for their association with HF risk. Objective: To assess whether baseline ECG abnormalities or dynamic changes are associated with an increased risk of HF. Method: A prospective cohort study of 2915 participants aged 70 to 79 years without a preexisting HF followed for a median period of 11.4 (IQR 7.0-11.7) years from the Health Aging and Body Composition study. The Minnesota Code was used to define major and minor ECG abnormalities at baseline and at 4-year. Main outcome measure was adjudicated incident HF events. Using Cox models, the (1) the association between ECG abnormalities and incident HF and (2) incremental value of adding ECG to the Health ABC HF Risk Score, was assessed. Results: At baseline, 380 participants (13.0%) had minor and 620 (21.3%) had major ECG abnormalities. During follow-up, 485 (16.6%) participants developed incident HF. After adjusting for the eight clinical variables in the Health ABC HF Risk Score, the hazard ratio (HR) was 1.27 (95% confidence interval [CI] 0.96-1.68) for minor and 1.99 (CI 1.61-2.44) for major ECG abnormalities (P for trend <0.001) compared to no ECG abnormalities. The association did not change according to presence of baseline CHD. At 4-year, 263 participants developed new and 549 had persistent abnormalities and both were associated with increased HF risk (HR = 1.94, CI 1.38-2.72 for new and HR=2.35, CI 1.82-3.02 for persistent compared to no ECG abnormalities). Baseline ECG correctly reclassified 10.6% of overall participants across the categories of the Health ABC HF Risk Score. Conclusion: Among older adults, baseline ECG abnormalities and changes in them over time are common; both are associated with an increased risk of HF. Whether ECG should be incorporated in routine screening of older adults should be evaluated in randomized controlled trials.

Effects of prior repeated-sprints with different recovery duration on oxygen uptake kinetics during subsequent heavy-exercise

Introduction: Prior repeated-sprints (6) has become an interesting method to resolve the debate surrounding the principal factors that limits the oxygen uptake (V'O2) kinetics at the onset of exercise [i.e., muscle O2 delivery (5) or metabolic inertia (3)]. The aim of this study was to compare the effects of two repeated-sprints sets of 6x6s separated by different recovery duration between the sprints on V'O2 and muscular de-oxygenation [HHb] kinetics during a subsequent heavy-intensity exercise. Methods: 10 male subjects performed a 6-min constant-load cycling test (T50) at intensity corresponding to half of the difference between V'O2max and the ventilatory threshold. Then, they performed two repeated-sprints sets of 6x6s all-out separated by different recovery duration between the sprints (S1:30s and S2:3min) followed, after 7-min-recovery, by the T50 (S1T50 and S2T50, respectively). V'O2, [HHb] of the vastus lateralis (VL) and surface electromyography activity [i.e., root-mean-square (RMS) and the median frequency of the power density spectrum (MDF)] from VL and vastus medialis (VM) were recorded throughout T50. Models using a bi-exponential function for the overall T50 and a mono-exponential for the first 90s of T50 were used to define V'O2 and [HHb] kinetics respectively. Results: V'O2 mean value was higher in S1 (2.9±0.3l.min-1) than in S2 (1.2±0.3l.min-1); (p<0.001). The peripheral blood flow was increased after sprints as attested by a higher basal heart rate (HRbaseline) (S1T50: +22%; S2T50: +17%; p≤0.008). Time delay [HHb] was shorter for S1T50 and S2T50 than for T50 (-22% for both; p≤0.007) whereas the mean response time of V'O2 was accelerated only after S1 (S1T50: 32.3±2.5s; S2T50: 34.4±2.6s; T50: 35.7±5.4s; p=0.031). There were no significant differences in RMS between the three conditions (p>0.05). MDF of VM was higher during the first 3-min in S1T50 than in T50 (+6%; p≤0.05). Conclusion: The study show that V'O2 kinetics was speeded by prior repeated-sprints with a short (30s) but not a long (3min) inter-sprints-recovery even though the [HHb] kinetics was accelerated and the peripheral blood flow was enhanced after both sprints. S1, inducing a greater PCr depletion (1) and change in the pattern of the fibres recruitment (increase in MDF) compared with S2, may decrease metabolic inertia (2), stimulate the oxidative phosphorylation activation (4) and accelerate V'O2 kinetics at the beginning of the subsequent high-intensity exercise.

Ihmisluonnosta, evoluutiopsykologiasta ja sosiobiologiasta

Vastine sosiologian professori Pekka Sulkusen ja toimittaja Osmo Tammisalon kirjoitukseen Tieteessä tapahtuu -lehdessä vuonna 2002.

Vanhenevat aivot

Kirjoittaja on professori Helsingin yliopiston Patologian osastolla, Haartman-instituutissa. Kirjoitus perustuu esitelmään Tieteen päivillä 8.1.2003.

Missä viipyvät Suomen nobelistit?

Kirjoitus perustuu Tieteen päivien avajaisissa 8.1.2003 pidettyyn esitelmään. Kirjoittaja on molekyylibiologian professori Karolinska Institutetissa ja toimii johtajana Tukholman syöpätutkimukseen keskittyvässä Ludwig-instituutissa. Hän on myös toiminut lääketieteellisessä Nobel-toimikunnassa vuodesta 1990 ja sen puheenjohtajana 1998-2000.

Voiko verkkotietoon luottaa?

Kirjoitus perustuu esitelmään Tieteen päivillä 8.1.2003. sessiossa "Tiede verkossa - bulkkia vai laatua?" Kirjoittaja on dosentti ja Tiedonjulkistamisen neuvottelukunnan puheenjohtaja sekä Suomalaisen Kirjallisuuden Seuran pääsihteeri.

Tekeekö tieteen kehitys ihmistieteet tarpeettomiksi?

Kirjoittaja on fil.tri ja dosentti sekä Helsingin yliopiston Tutkijakollegiumin tutkija. Kirjoitus perustuu juhlapuheeseen Helsingin yliopiston humanistisen tiedekunnan ja matemaattis-luonnontieteellisen tiedekunnan 150-vuotisjuhlassa 15.11. 2002.

Itsekkäät geenit sosiaalisissa yhteisöissä

Kirjoitus perustuu esitelmään Tieteen päivillä 9.1.2003. Kirjoittaja on Oulun yliopiston perinnöllisyystieteen professori.

Katseessa estotonta elämisen ahneutta

Kirjoittaja on toiminut Helsingin yliopiston poliittisen historian dosenttina vuodesta 1978 ja Palménin kanslerikauden lopulla yliopiston tiedotuspäällikkönä 1981-1984.

Tieteen ja "taiteen" eroista

Vastine Osmo Tammisalon kommenttiin Tieteessä tapahtuu -lehdessä 8/2002 puheenvuoroon "Sosiologia ei konservatiivista"

Immateriaalioikeudet - tutkimuksen turva vai este?

Kirjoittaja on siviilioikeuden dosentti Helsingin yliopistossa ja johtaa Suomen Akatemian rahoittamaa projektia "Legal and Socio-Cultural Contours of Intellectual Property Rights". Kirjoitus perustuu esitelmään Tieteen päivillä 8.1.2003. tilaisuudessa "Tieto verkossa - bulkkia vai laatua?".