NAP: Competition (2007)

Citation:

Kimber NE, Ross JJ, Mason SL, Speedy DB. Energy balance during an Ironman Triathlon in male and female triathletes. Int J Sport Nutr Exerc Metab. 2002; 12 (1): 47-62.

PubMed ID: 11993622
 
Study Design:
Non-Randomized Controlled Trial
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To investigate the energy balance of triathletes participating in an Ironman event.
Inclusion Criteria:
  • Athletes living in Auckland City, where race was held
  • Athletes whose estimated race times were between 10.5 and 14 hours
  • All subjects were healthy, with no significant medical illnesses
  • No consumption of medication.
Exclusion Criteria:
Excluded if not included above.
Description of Study Protocol:
  • Recruitment: Subjects were recruited from the 1997 New Zealand Ironman triathlon
  • Design: Non-randomized clinical trial
  • Intervention: Energy intake and energy expenditure was monitored during an Ironman event (3.8-kilometer swim, 180-kilometer cycle, 42.2-kilometer run).

Statistical Analysis

  • Gender differences for physical characteristics, energy intake and energy expenditure variables were tested using a one-way ANOVA
  • Within-group differences between food and fluid intake for females were also tested using a one-way ANOVA
  • Relationships betwen variables are reported as Pearson Product-Moment Correlation Coefficients.
Data Collection Summary:

Timing of Measurements

All measurements were taken during the Ironman triathlon.

Dependent Variables

  • Energy intake was monitored at seven designated points by dietary recall of food and fluid consumption
  • Energy expenditure was calculated using equations based on heart rate, as measured by Sports Tester PE 3000
  • Interviewers ran or cycled with the athletes for a short distance and interviewed athletes at transitions.

Independent Variables

Ironman triathlon.
Description of Actual Data Sample:
  • Initial N: 18 subjects (eight females, 10 males)
  • Attrition (final N): 18
  • Mean age
    • Females: 34.3±7.0 years
    • Males: 36.2±9.6 years.
  • Ethnicity: Not mentioned

Other Relevant Demographics

  • Anthropometrics: Males were significantly different from females for height, weight, body fat percentage and fat-free mass, as would be expected between genders
  • Location: Auckland.
Summary of Results:

Relationships Between Energy and Carbohydrate Intake, Energy Balance and Finishing Time in the Ironman Triathlon

  Females Males
Kcals, Total 0.74, P<0.05 0.01

Kcals, Cycle

0.80, P<0.05

0.20

Kcals, Run 0.51 -0.55
CHO (g), Total 0.72, P<0.05 -0.03
CHO (g), Cycle 0.77, P<0.05 0.16
CHO (g), Run 0.46 -0.59
CHO (g per kg per hour), Total 0.48 -0.12
CHO (g per kg per hour), Cycle 0.59 0.32
CHO (g per kg per hour), Run 0.30 -0.75, P<0.05

Energy Balance

-0.31

0.15

Other Findings

  • Total energy expenditure (10,036±931kcal and 8,570±1,014kcal) was significantly greater than total energy intake [3,940±868 and 3,115±914 kcal (P<0.001)] for males and females, respectively, although energy balance was not different between genders
  • Finishing time was inversely related to carbohydrate intake during the marathon run for males (R=-0.75, P<0.05) and not females.
Author Conclusion:
  • The major finding of this study is that despite the large negative energy balance, mean energy intake appeared sufficient for all subjects in this study to finish the Ironman before reaching exhaustion from substrate depletion. In support of this finding, rates of carbohydrate intake were adequate to meet maximal rates of plasma glucose oxidation by skeletal muscle.
  • Carbohydrate intake may have been a factor contributing to improved performance during the latter stages of an Ironman for male athletes. Indeed, increasing energy intake, primarily in the marathon run, may have improved performance for males. In contrast, increasing carbohydrate and total energy intake during the Ironman did not relate to faster finishing times in female triathletes, suggesting other factors were important for improving performance.
  • It remains to be determined if ultra-distance triathletes can optimize their energy intake in relation to energy expenditure to maximize performance during an Ironman triathlon.
Funding Source:
University/Hospital: Lincoln University
Not-for-profit
0
Foundation associated with industry:
Reviewer Comments:
  • Energy expenditure based on heart rate may not be valid measurement
  • Dietary recalls of food and fluid during the triathlon may be questionable.
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) Yes
  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? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
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? Yes
  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? ???
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? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  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.) N/A
  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? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  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? N/A
  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.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  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? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  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? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  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? ???
  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? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? ???
  7.5. Was the measurement of effect at an appropriate level of precision? ???
  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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  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? N/A
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? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes