Changes in VO2max and cardiac output in response to short-term high-intensity interval training in Caucasian and Hispanic young women: A pilot study

Data obtained in primarily Caucasian (C) and African American adults show that ethnicity does not mediate responsiveness to exercise training. It is unknown if Hispanics (H), who face elevated health risks and are less active than C, exhibit a similar response to exercise training. This study compared cardiorespiratory and hemodynamic responses to high intensity interval training (HIIT) between C and H women. Twelve C and ten H women ages 19–35 yr who were non-obese and inactive completed nine sessions of HIIT over a 3 wk period. Maximal oxygen uptake (VO2max) was assessed twice at baseline during which thoracic impedance was used to evaluate heart rate (HR), stroke volume (SV) and cardiac output (CO). Habitual physical activity was assessed using accelerometry. Results showed a significant main effect of training for VO2max in C and H (F = 13.97, p = 0.001) and no group by training interaction (p = 0.65). There was a main effect of training for CO and SV in C and H (F = 7.57, p = 0.01; F = 7.16, p = 0.02), yet post hoc analyses revealed significant increases were only exhibited in C. There was a tendency for a group by training interaction for a-VO2diff (F = 1.32, p = 0.054), and a large effect size was seen in H (d = 1.02). Overall, data show no effect of ethnicity on changes in VO2max with low-volume HIIT, yet C and H may achieve this outcome differently. Longer studies in similar populations are needed to verify this result.


Introduction
Background 2 Scientific background and explanation of rationale Yes 2 Theories used in designing behavioral interventions Yes 2,3

Participants 3
Eligibility criteria for participants, including criteria at different levels in recruitment/sampling plan (e.g., cities, clinics, subjects)

Yes 5
Method of recruitment (e.g., referral, self-selection), including the sampling method if a systematic sampling plan was implemented Yes 5

Recruitment setting
No Settings and locations where the data were collected

Yes 6
Interventions 4 Details of the interventions intended for each study condition and how and when they were actually administered, specifically including: Yes 5-9 o Content: what was given? Methods used to collect data and any methods used to enhance the quality of measurements Yes 5-9 Information on validated instruments such as psychometric and biometric properties Yes 5-9 Sample Size 7 How sample size was determined and, when applicable, explanation of any interim analyses and stopping rules

No
Assignment Method 8 Unit of assignment (the unit being assigned to study condition, e.g., individual, group, community)

No
Method used to assign units to study conditions, including details of any restriction (e.g., blocking, stratification, minimization)

No
Inclusion of aspects employed to help minimize potential bias induced due to non-randomization (e.g., matching)

Yes 6
Blinding (masking) 9 Whether or not participants, those administering the interventions, and those assessing the outcomes were blinded to study condition assignment; if so, statement regarding how the blinding was accomplished and how it was assessed.

No
Unit of Analysis 10 Description of the smallest unit that is being analyzed to assess intervention effects (e.g., individual, group, or community)

Yes 8
If the unit of analysis differs from the unit of assignment, the analytical method used to account for this (e.g., adjusting the standard error estimates by the design effect or using multilevel analysis)

No
Statistical Methods

11
Statistical methods used to compare study groups for primary methods outcome(s), including complex methods of correlated data

Yes 9
Statistical methods used for additional analyses, such as a subgroup analyses and adjusted analysis

Yes 9
Methods for imputing missing data, if used

No
Statistical software or programs used Yes 9

Results
Participant flow 12 Flow of participants through each stage of the study: enrollment, assignment, allocation, and intervention exposure, follow-up, analysis (a diagram is strongly recommended)

Yes 10
o Enrollment: the numbers of participants screened for eligibility, found to be eligible or not eligible, declined to be enrolled, and enrolled in the study

Yes 10
o Assignment: the numbers of participants assigned to a study condition No o Allocation and intervention exposure: the number of participants assigned to each study condition and the number of participants who received each intervention No o Follow-up: the number of participants who completed the followup or did not complete the follow-up (i.e., lost to follow-up), by study condition

Yes 10
o Analysis: the number of participants included in or excluded from the main analysis, by study condition

Yes 10
Description of protocol deviations from study as planned, along with reasons

Recruitment 13
Dates defining the periods of recruitment and follow-up

Yes 6
Baseline Data 14 Baseline demographic and clinical characteristics of participants in each study condition

Yes 6
Baseline characteristics for each study condition relevant to specific disease prevention research

No
Baseline comparisons of those lost to follow-up and those retained, overall and by study condition

No
Comparison between study population at baseline and target population of interest

No
Baseline equivalence 15 Data on study group equivalence at baseline and statistical methods used to control for baseline differences

Yes 6
Numbers analyzed 16 Number of participants (denominator) included in each analysis for each study condition, particularly when the denominators change for different outcomes; statement of the results in absolute numbers when feasible Yes 10-12 Indication of whether the analysis strategy was "intention to treat" or, if not, description of how non-compliers were treated in the analyses

No
Outcomes and estimation 17 For each primary and secondary outcome, a summary of results for each estimation study condition, and the estimated effect size and a confidence interval to indicate the precision Yes 10-12 Inclusion of null and negative findings Yes 10-12 Inclusion of results from testing pre-specified causal pathways through which the intervention was intended to operate, if any Generalizability 21 Generalizability (external validity) of the trial findings, taking into account the study population, the characteristics of the intervention, length of follow-up, incentives, compliance rates, specific sites/settings involved in the study, and other contextual issues