EAL

NAP: Energy Balance and Body Composition (2007)

Citation:

Noel MB, VanHeest JL, Zaneteas P, Rodgers CD. Body composition in Division I football players. J Str Cond Res. 2003; 17 (2): 228-237

PubMed ID: 12741857

Study Design:

Class:

C - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

To evaluate body composition across playing positions in a group of NCAA Division I football players (Michigan State University)
To compare body composition of current collegiate football players with that of players in the early 1980s and early 1990s
To determine if players in positions that have tended to focus on an increase in size over the past several years also demonstrate an increase in body fat percentage.

Inclusion Criteria:

Male football players from a Division I football team (Michigan State University)
Actively engaged in fall/winter season practices including a regular maintenance strength training program at time of evaluation.

Exclusion Criteria:

None specified.

Description of Study Protocol:

Recruitment

From the Michigan State University football team.

Design

Case-control study; compared current findings to those players in studies from 1980s and early 1990s.

Statistical Analysis

Sum of skinfolds, skinfold thickness, body density, FFM and body fat percentage were compared across position group and within each sub-category using ANOVA techniques
Significant pairwise differences were determined using the Scheffe post-hoc test
Data presented as means±SEM.

Data Collection Summary:

Timing of Measurements

Players asked to come in twice during a two-week period, both times in a state of normal hydration
Height, body weight, BMI and skinfold measurements were taken during the first visit
Hydrostatic weighing was performed during the second session.

Dependent Variables

Skinfold thickness (Lange skinfold calipers; taken at triceps, biceps, subscapular, chest, abdomen, superior iliac, thigh and calf sites)
Height (Stadiometer)
Body weight (Health-O-Meter)
Body density (hydrostatic weighing)
Body composition (using the Sloan formula).

Independent Variables

Football playing position.

Description of Actual Data Sample:

Initial N: 69 males
Attrition (final N): 69; only 25 players were willing to participate in hydrostatic weighing
Age: See results
Ethnicity: 35 white, 34 African-American.

Other Relevant Demographics

Players separated into six groups:

Offensive linemen and tight ends (OL/TE)
Defensive linemen (DL)
Offensive backs and receivers (RB/WR)
Defensive backs (DB)
Linebackers (LB)
Quarterbacks and kickers (QB/K).

Location

Michigan State University.

Summary of Results:

	OL/TE (N=16)	DL (N=14)	RB/WR (N=15)	DB (N=12)	LB (N=6)	QB/K (N=6)	Pooled Mean (N=69)
Age (years)	19.7±0.3	19.4±0.3	19.5±0.3	19.8±0.3	20.2±0.5	19.3±0.6	19.6±0.1
Height (cm)	190.6±1.2	190.1±1.9	177.3±1.4,*	182.4±1.1,*	188.3±1.2*	181.2±2.8*	185.1±0.9
Body mass (kg)	122.4±4.7	110.5±5.4	86.6±2.9,*	86.9±1.3,*	104.1±4.7	84.8±1.8,*	101.2±2.5
BMI	33.6±1.0	30.8±1.6	27.6±1.0*	26.7±0.5*	29.4±1.3	25.8±0.5*	29.4±0.6
Ponderal index	10.13±0.16	10.72±0.37	11.18±0.17*	11.43±0.11*	10.82±0.25	11.50±0.10*	10.96±0.19
Sum of skinfolds (mm)	160.8±9.8	150.0±18.0	92.7±11.0*	88.8±6.2*	110.2±14.7	100.42±14.7	121.6±6.5
Hydrostatic Weighing
	OL/TE (N=8)	DL (N=5)	RB/WR (N=2)	DB (N=7)	LB (N=0)	QB/K (N=2)
Body fat percentage	21.07±2.37	16.3±0.84	7.48±2.48	8.24±0.97	NA	10.45±1.05

* P≤0.05 vs. OL/TE group

** P≤0.05 vs. DL group

Data presented as means±SEM.

Player Position	Body Density (BD)	Fat-Free Mass (FFM; kg)	Body Fat Percentage
OL/TE	1.0421±0.004	90.57±3.0	25.4±2.0
DL	1.0395±0.008	77.96±2.4*	27.4±3.6
RB/WR	1.0664±0.005**	71.15±1.0*	17.0±1.9
DB	1.0685±0.002,*	73.6±0.9*	15.2±1.0**
LB	1.0543±0.010	81.87±3.3	20.6±4.5
QB/K	1.0644±0.005	71.39±2.0	15.8±1.7
Pooled Mean	1.0544±0.005	71.39±2.0	15.8±1.7

* P≤0.05 vs. OL/TE group** P≤0.05 vs. DL group

Data presented as means±SEM.

Other Findings

When compared to data from Smith and Mansfield (Med Sci Sports Exerc. 1984; 16: 398-405), it appears that players at all positions have a much higher body fat percentage, although no measures of significance are provided.

Author Conclusion:

The results of this study suggest that:

The increase in total body mass that has been observed in Division I football players over the past several years has also been accompanied by an increase in body fat percentage, with the ultimate result being that some players are not only overweight by usual standards, but over-fat as well.
Implications from these conclusions are significant from a functional performance perspective: They are most significant from the standpoint of the athlete's overall health and medical prognosis.

Funding Source:

University/Hospital:

Michigan State University, University of Connecticut, University of Toronto

Reviewer Comments:

Athletic performance was not a measured outcome.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	N/A
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	N/A
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	N/A

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	N/A
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		Yes
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	Yes
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	No
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	No
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		N/A
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	N/A
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	N/A
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	N/A
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	???
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	No
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	No
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	No
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		???
	10.1.	Were sources of funding and investigators' affiliations described?	No
	10.2.	Was the study free from apparent conflict of interest?	Yes