The Football Scientist - 29th March 2024
Football Fitness Mentorship Community
This week on the football fitness mentorship community, we uploaded brand new educational videos for our members to learn and apply into their own practice.
One such video was discussing the use of GPS thresholds to monitor players. There is often confusion around which thresholds to use, whether using absolute vs relative (or a combination of the two).
You can check out a preview of the video below.
We currently have no places available left to join this month. Due to high demand, we will be releasing 5 new places to join next month.
For more details about the community and to submit an enquiry to join the wait list, check out the link here.
Research Weekly Summary
The Ratio between Weekly Training and Match External Physical Loads
Kokstejn, J., Vampola, J., Musalek, M., Grobar, M., & Stastny, P. (2024). The Ratio between Weekly Training and Match External Physical Loads in U17 Elite Youth Soccer Players: Implications for the Training Process. Journal of Sports Science and Medicine, 23(1), 107-113.
Research Background:
There's limited research on the external physical load experienced by elite youth soccer players during both training sessions and official matches throughout the weekly microcycle. This study aimed to address this gap by investigating differences in external physical load across player positions in U17 elite youth soccer players during official matches and determining the weekly training-to-match physical load ratio (WTMLr) across player positions.
Methods:
The study included 20 outfield players from an elite soccer academy. Data were collected during the spring in-season period, focusing on 17 official matches played in a 4-3-3 game format. External physical load indicators monitored included total distance (TD), total distance in high-speed running (HSR; > 16.1 km/h), total distance in sprint running (SPR; > 21.6 km/h), and relative physical load intensity (%HSR). The WTMLr was calculated for TD, HSR, SPR, and %HSR as the ratio of the average weekly sum of training physical load to the average sum of physical load in an official match for a given player's position.
Key Findings:
- The training intensity during a one-week microcycle (%HSR in WTMLr) only achieved 76% of match demands.
- Central defenders (CD) performed significantly lower in all measured indicators of external physical load during official matches compared to all other positions, except for TD in Strikers (S).
- Strikers achieved significantly higher SPR during official matches compared to central defenders, central midfielders, and full-backs.
- Central defenders reported higher WTMLr (with medium-large effect sizes) in HSR and SPR indicators compared to all other positions.
- Central midfielders performed significantly higher %HSR in WTMLr compared to Strikers and full-backs.
Study Limitations:
Limitations include the focus on a specific age group and player positions within an elite soccer academy, which may limit generalizability. Additionally, other factors influencing physical load, such as technical and tactical aspects, were not fully considered.
Check out the article here.
Energy expenditure and dietary intake in professional female football players
Brinkmans, N., Plasqui, G., van Loon, L., & van Dijk, J. W. (2024). Energy expenditure and dietary intake in professional female football players in the Dutch Women’s League: Implications for nutritional counselling. Journal of Sports Sciences, 1-10.
Research Background:
While there is considerable research on the nutritional needs of male football players, studies focusing on female football players are limited. This study aimed to assess the total daily energy expenditure (TDEE) of professional female football players, examining factors such as body composition, physical activity, and dietary intake.
Methods:
Fifteen professional female football players from the highest Dutch Women’s League participated in this observational study. TDEE was measured using doubly labelled water over a 14-day period, and additional measurements included resting metabolic rate (RMR), fat-free mass (FFM), and dietary intake assessed through 24-hour recalls. Physical activity energy expenditure (PAEE) was calculated by subtracting RMR and estimated diet-induced thermogenesis from TDEE.
Key Findings:
- The average TDEE was 2882 ± 278 kcal/day, with a significant correlation observed between TDEE and FFM (r = 0.62).
- PAEE was found to be 1207 ± 213 kcal/day.
- Weighted energy intake averaged 2344 kcal [2023–2589].
- Carbohydrate intake varied across different days, with averages of 3.2 ± 0.7 g/kg body mass on rest days, 4.4 ± 1.1 g/kg body mass on training days, and 5.3 ± 1.9 g/kg body mass on match days.
- Weighted mean protein intake was 1.9 ± 0.4 g/kg body mass.
Study Limitations:
The study's limitations include its observational nature and the relatively small sample size of professional female football players from the highest Dutch Women’s League. Additionally, dietary intake was assessed through 24-hour recalls, which may not capture long-term dietary patterns accurately.
Check out the article here.
Injury prevention programme in male young football players
Obërtinca R, Meha R, Hoxha I, Shabani B, Meyer T, Aus der Fünten K (2024). Efficacy of a new injury prevention programme in male young football (soccer) players: a cluster-randomised controlled trial . British Journal of Sports Medicine, In Press.
Research Background:
While injury prevention programs are widely recognized in football, there's a scarcity of evidence on the efficacy of such programs, especially among adolescent players. This study aimed to evaluate the effectiveness of a new multicomponent, exercise-based injury prevention program in football players aged 13–19 years.
Methods:
A two-arm cluster-randomized controlled trial was conducted, with clubs as the unit of randomization. Fifty-five football teams from Kosovo, comprising under 15, under 17, and under 19 age groups, were randomly assigned to either the intervention (INT; 28 teams) or control group (CON; 27 teams) and followed for one football season (August 2021–May 2022). The INT group implemented the 'FUNBALL' program at least twice per week after their regular warm-up, while the CON group continued with their usual training routine. The primary outcome measure was the overall number of football-related injuries, with secondary outcomes including region-specific injuries of the lower limbs and injury severity.
Key Findings:
- A total of 319 injuries occurred, with 132 in the INT group and 187 in the CON group.
- The INT group utilized the 'FUNBALL' program in 72.2% of all training sessions, on average 2.2 times per week.
- The INT group showed a significantly lower incidence of overall injuries (incidence rate ratio [IRR] 0.69, 95%CI 0.55 to 0.87), thigh injuries (IRR 0.62, 95%CI 0.39 to 0.98), moderate injuries (IRR 0.65, 95%CI 0.44 to 0.97), and severe injuries (IRR 0.51, 95%CI 0.28 to 0.91) compared to the CON group.
Study Limitations:
Limitations of the study include its focus on male adolescent football players and the specific context of football clubs in Kosovo, which may limit the generalizability of the findings to other populations and settings.
Check out the article here.
Podcast Episode of the Week
Science for Sport Podcast
On the episode, Simon Hartley (sport psychology consultant) discusses where motivation comes from, how to stay motivated and how athletes use motivation for performance.
Post of the Week
Tim Gabbett
In this post, Tim highlights the importance of not only focusing solely on sprinting when it comes to hamstring rehab. It’s important to also consider the local tissue capacity, which can be loaded through isolated exercises.
See link to the post.
Thank you for reading, see you next week.
James
p.s. Whenever you are ready, check out how I can help you further:
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