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Hydration

Hydration and Physical Activity

Citation:

White JA, Pomfret D, Rennie S, Gissane C, Womg J, Ford M.  Fluid replacement needs of well-trained male and female athletes during indoor and outdoor steady-state running, J Sci and Medicine in Sport 1998; 1 (3): 131-42. 

PubMed ID: 9783515
 
Study Design:
crossover study, conditions administered in counter-balanced fashion: Outdoor No fluid, water, sportsdrink; Indoor no fluid, water, sports drink.
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To investigate the fluid replacement needs of male and female athletes during indoor and outdoor steady-state running, and relate these to the hemodynamic physiological and blood chemistry changes associated with such performance. 

Inclusion Criteria:

well-trained, middle-distance athletes; informed consent; no others mentioned.

Exclusion Criteria:

none mentioned.

Description of Study Protocol:

Recruitment not mentioned.

 Design

 counter-balanced crossover design. 

Blinding used (if applicable)

 not mentioned.

Intervention (if applicable)

Test beverages (4C) administered at 15 min intervals during exercise indoors and outdoors. 

no drink, water, or

5.58%CES (carbonated; 850 kj/l; 21.7 mmol/l Na; 2.56 mmol/l K, 1.55 mmol/l Ca, 0.41 mmol/l Mg, 0.14 mmol/l Cl, 5.32 mmol/l PO, 3.6 pH) 

Statistical Analysis

 Repeated measures ANOVA in 2*2*3 factorial design (conditions*gender*treatment); nesting factor 2 (gender).  Pre- to post-run differences analyzed; multiple comparison of means using Scheffe test; Sig level P<0.05.

Data Collection Summary:

Timing of Measurements

 1-h steady-state runn on treadmaill (indoors) and on track (outdoors) at speed equivalent to 75% VO2max; running speed for M, F (4.69±0.06 and 3.77±0.11 m/s).  Fluid administered at 15 min intervals during run, and terminated 15 min after run.  Consisten environmental conditions experienced during indoor and outdoor conditions.

Physiological measurments made prior to and upon completion of run. 

Dependent Variables

  • HR
  • body temp
  • body mass change
  • blood lactate (analox)
  • Hgb (Hgb meter)
  • Pvol (Dill & Costill)
  • Blood glucose (enzymatic colorimetric method)
  • Running performance

Independent Variables

 drink condition (no drink, water, CES)

Indoor vs. outdoor.

Control Variables

 drink temp and volume; controlled training schedules for athletes during study; maintained dietary intake consistent during study; ran alone; smae clothing worn in both tests.

Description of Actual Data Sample:

 

Initial N: N=18 (12 M, 6 F)

Attrition (final N): N=18 (12 M, 6 F)

Age: see table below

Ethnicity: not mentioned.

Other relevant demographics: none mentioned.

Anthropometrics (e.g., were groups same or different on important measures)

Subject characteristics
  M, N=12 F, N=6
Age (yr) 25.0±3.6 22.7±1.0
Ht (cm) 172.8±3.2* 165.3±3.0
Mass (kg) 64.4±1.6 61.5±3.0
BSA (m2) 1.77±0.4* 1.66±0.4
VO2peak (ml/kg/min), pre-; post-study 72.7±1.1*; 72.0±0.9* 64.0±3.3; 62.8±3.4

*P<0.05, M vs F.

Location:

 UK

Summary of Results:

 

*no tabular data given - all figures*

 

Findings

NS differences found between indoor and outdoor no-drink condition for change in body mass. 

There was a sig greater absolute and relative body mass loss in M (vs F) under both indoor and outdoor in the no-drink condition (P<0.05).

Both M & F: sig greater Pvol changes during indoor vs outdoor in no-drink, vs 2 other drink conditions (P<0.05).  NS differences in Pvol changes  between M and F within 2drink conditions, neither in- or outdoors. 

Mean body temp changes sig lower in M vs F during indoor vs outdoor with CES (P<0.05).  Body temp changes sig lower in M vs F after outdoor vs indoor condition in both no-fluid, and water treatment (P<0.05).  NS difference in F.

HR changes sig lower during outdoor vs indoor conditions in all 3 drink conditions for both M and F (P<0.05).  Greater HR changes in M vs F (P<0.05) during indoor and outdoor conditions in all 3 treatments. 

Blood lactate changes greater in F vs M during both conditions in the 3 treatments (NS).  In M, greater blood lactate changes during outdoor vs indoor in the 3 treatments (P<0.05).  NS differences in blood lactate between the 3 treatments for M, F, or indoor and outdoor.

Blood glucose sig greater and positively changed in < and F during both indoor and outdoor CES conditions (P<0.01), versus the negative changes during both indoor and outdoor no-drink and water treatments.  NS differences in blood glu between M and F, neither in no-drink, water, and CES treatments, nor in indoor or outdoor. 

Sig (P<0.05) interaction:  CES more pronounced in indoor vs outdoor condition among both M and F.

 

Author Conclusion:

In response to prolonged indoor and outdor steady-state running, there appear to be significant gender-specific differences in the fluid replacement requirments of middle-distance athletes.  Gender-specific fluid replacement strategies should be used in order to minimize physiological, hemodynamic and blood chemistry disturbances in these athletes. 

Funding Source:
Industry:
Smithkline Beecham
Pharmaceutical/Dietary Supplement Company:
Reviewer Comments:

measurement of running performance not described.

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
  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
  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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.1. 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? ???
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? ???
  1.3. Were the target population and setting specified? Yes
  1.3. Were the target population and setting specified? Yes
  2. Was the selection of study subjects/patients free from bias? ???
2. Was the selection of study subjects/patients free from bias? ???
  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
  2.1. 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
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? 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? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
  3. Were study groups comparable? 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
  3.1. 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
  3.2. 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.) 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
  3.4. 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
  3.5. 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
  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. Was method of handling withdrawals described? N/A
  4.1. Were follow-up methods described and the same for all groups? 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
  4.2. 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? 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
  4.4. 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
  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? ???
5. Was blinding used to prevent introduction of bias? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  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
  5.2. 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
  5.3. 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
  5.4. 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
  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. 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
  6.1. 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? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  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
  6.4. 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? 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
  6.6. 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? 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? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? Yes
  7. Were outcomes clearly defined and the measurements valid and reliable? Yes
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
  7.1. 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
  7.2. 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
  7.3. 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? Yes
  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
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  7.7. Were the measurements conducted consistently across groups? Yes
  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. 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
  8.1. 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
  8.2. 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
  8.3. 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
  8.4. 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
  8.5. 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? ???
  8.6. Was clinical significance as well as statistical significance reported? ???
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
  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. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? 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. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes
  10.2. Was the study free from apparent conflict of interest? Yes