Malte Nejst Larsen is defending his PhD thesis at The Department of Nutrition, Exercise and Sports on Friday, November 11, at 14:00.

malte-nejst-larsenMalte Nejst Larsen is defending his PhD thesis Fitness and Health Effects of Frequent Intense Training in 8-10-year-old Danish Children at the Department of Nutrition, Exercise and Sport, Store Auditorium, Nørre Allé 53, 2200 Copenhagen.

Physical activity plays a crucial role in preventing a number of lifestyle diseases. Previously studies show that children who are involved in regular activities in sports clubs, have better cardio-vascular and bone health than children who are not members of a sports club. Furthermore  team sports seems to have a positive effect on bone mineral content and bone mineral density compared to individual sports.

In this PhD thesis the effects in children who had normal school exercise is compared with children exposed to 1-2 hours pr. week of school-based high intense exercise in the form of small sided ballgames, interval running or ‘circuit strenght training’ consisting of gymnastic and strengthening exercises.

The thesis shows that 2 hours of intense school exercise pr. week have significant positive effects on bone mineral density, muscle strength and balance for 8-10 year old children. Read the full abstract below.


  • Professor Christian Mølgaard (chair), Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
  • Professor Lars Bo Andersen, Faculty of Teacher Education and Sport, Sogn and Fjordane University Colleage, Sogndal, Norway, and University of Southern Denmark, Odense, Denmark
  • Associate Professor Ingegerd Ericsson, Department of Sport Sciences, Malmø University, Sweden


  • Professor Peter Krustrup, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark

Co supervisor

  • Professor Jens Bangsbo, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark

List of papers

  • Randers MB, Andersen TB, Rasmussen LS, Larsen MN, Krustrup P (2014). Effect of game format on heart rate, activity profile, and player involvement in elite and recreational youth players. Scand J Med Sci Sports 24(S1): 17-26.
  • Larsen MN, Nielsen CM, Ørntoft C, Randers MB, Manniche V, Hansen L, Hansen PR, Bangsbo J, Krustrup P (2016). Physical fitness and body composition in Danish 8-10-year-old children related to voluntary sports club involvement and gender. BioMed Res Int, in revision.
  • Larsen MN, Nielsen CM, Helge EW, Madsen M, Manniche V, Hansen L, Hansen PR, Bangsbo J, Krustrup, P (2016). Positive effects on bone mineralisation and muscular fitness after 10 months of intense school-based physical training for 8-10-year-old children (The FIT FIRST study). Br J Sports Med, online first, June 13, 2016. DOI: 10.1136/bjsports-2016-096219.
  • Larsen MN, Nielsen CM, Helge EW, Madsen M, Manniche V, Hansen L, Hansen PR, Bangsbo J, Krustrup, P (2016). Fitness effects of 10 months frequent low-volume ball game training or interval running for 8-10-year old schoolchildren. Eur J Appl Physiol, in revision.


Physical activity for children has been much debated in recent years. Everyone has seemed to agree that it is important for children to exercise for the sake of physiological health, but cognitive functions and psycho-social behaviour are now also considered to be affected by physical activity. In fact, the evidence of beneficial effects convinced Danish politicians to design a school curriculum with 45 minutes of physical activity every day, which should enable every child to fulfil the recommendations of 60 minutes of moderate to vigorous physical activity (MVPA) every day when supplemented with organised and unorganised leisure time activities. The issues addressed in this thesis are the physiological responses to small-sided football and other high-intensity activities.

Paper I showed that recreational small-sided football games are highly intense for 9-12-year-old boys and that 5v5 provides for great involvement of all players compared to 8v8. For U10 players, no difference was found between 5v5 and 8v8 games in total distance covered (1754±237 (±SD) vs 1771±314 m, P=0.650, d=0.06), peak speed (18.5±1.5 vs 18.9±1.7 km∙h-1, P=0.188, d=0.24) and player load (251±44 vs 239±57 arbitrary units (AU), P=0.055; d=0.24). During 5v5 games, higher mean HR (174±10 vs 168±12 bpm, P=0.001, d=0.59) and number of technical actions (65.1±24.0 vs 36.9±20.4, P<0.001, d=1.27) were observed compared to 8v8 games.

Paper II showed that 8-10-year-old school children active in sports clubs had better (P<0.05) YYIR1C (33%, 767±26 vs 575±29 m), 20-metre sprint (3%, 4.33±0.03 vs 4.48±0.04 s), coordination (6%, 68±1 vs 72±1 s) and balance test performances (9%, 19.3±0.5 vs 21.2±0.7 falls/min) and lower fat mass index (FMI) (16%, 3.8±0.1 vs 4.5±0.2 kg(fat)·m-2) than children not active in sport clubs. Ball game players had better (P<0.05) YYIR1C (38%, 925±39 vs 671±28 m), 20-metre sprint (4%, 4.25±0.03 vs 4.42±0.04 s) and coordination test performances (5%, 65±1 vs 69±1 s), along with higher (P<0.05) lean body mass (LBM) (5%, 24.00±0.22 vs 22.83±0.25 kg) and whole-body BMD (2%, 0.90±0.00 vs 0.88±0.00 g/cm2) compared to children active in other sports.

Paper III and IV described the long-term training effects of frequent intense small-sided ball games (SSG), interval running (IT) and circuit strength training (CST) for 8-10-year-old school children. Analysis of baseline-to-10-months change scores showed between-group differences in favour of the 3×40 minute interventions in whole-body aBMD (SSG vs CON: 8 mg/cm2, 95%CI: 3-13; CST vs CON: 7 mg/cm2, 95%CI: 2-13, P<0.05) and leg BMC (SSG vs CON: 11 g, 95%CI: 4-18; CST vs CON: 11 g, 95%CI: 3-18, P<0.05). SSG produced higher change scores in leg aBMD compared to CON and CST (SSG vs CON: 19 mg/cm2, 95%CI: 11-39, P<0.001; SSG vs CST: 12 mg/cm2, 95%CI: 3-21, P=0.017), and CST produced higher change scores in whole-body BMC compared to CON (CST vs CON: 25 g, 95%CI: 10-39, P<0.05). Both types of training resulted in higher change scores compared to CON in postural balance (SSG vs CON: 2.4 fewer falls/min, 95%CI: 0.3-4.5, CST vs CON:3.6 fewer falls/min, 95%CI: 1.3-5.9, P<0.05) and jump length (SSG vs CON: 10%, 95%CI: 5-16%; CST vs CON: 9%, 95%CI: 3-15%, P<0.05) and that 5×12 minutes IR had positive effects (P<0.05) on 20-metre sprint performance (IR vs CON: 154 ms [95% CI 61–241 ms]).

In conclusion, the heart rates and distances covered with high-intensity running are high in youth football matches irrespective of the game format and level of play. Playing with fewer players on smaller pitches results in minor changes to physical loading but increases the technical involvement of players at elite and recreational level, which supports the use of small-sided games for youth players in football clubs. The exercise intensity (HR as well as player load) was also shown to be high during SSG in a school setting, as well as during IR and CST.

Results from the intervention study demonstrate that significant structural and functional musculoskeletal adaptations can be achieved from well-controlled high-intensity training in a school-based setting, especially from 3×40 minutes of SSG and CST. The overall fitness effects of the low-volume training (5×12 minutes of SSG or IR) were limited, yet positive effects were seen in sprint performance in the interval running group and in cardiovascular strain during submaximal exercise in the ball game group as well as in the interval running group, among those with low aerobic fitness levels.

Future studies will investigate other aspects of using small sided ball games in schools as part of physical education.

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