Abstract
Cancer treatment increases survivors risk for cardiorespiratory and cardiovascular
diseases, alterations of body composition, and loss of muscular strength. Regular physical
activity can be an effective strategy to reduce the risk of non-cancer related death among cancer
survivors. Recently, high intensity functional training (HIFT) has been identified as an
effective modality for improving fitness, body composition and muscle strength in cancer
survivors. The primary aim of this study was to determine the effect of HIFT on
cardiorespiratory fitness, cardiovascular health, physical function, and body composition in
breast cancer survivors previously treated with chemotherapy and/or radiation therapy. It was
hypothesised that high intensity functional training will be safe and effective at increasing
fitness, body composition and strength in breast cancer survivors, with a null hypothesis of no
change seen in these variables. The exercise intervention involved a 20-week HIFT program,
utilizing a variety of exercise modalities, including aerobic (walking/running, rowing, cycling),
resistance (machines, dumbbells, kettle bells) and body weight exercises (e.g. squats, push
ups). Participants exercised twice weekly, with each session lasting approximately 30-minutes.
The HIFT intervention sessions included 12 exercise stations, with participants exercising at
each station for 2-minutes, before having 30-seconds to move to the next station. Physical
function was measures through balance and functional tests, cardiorespiratory fitness assessed
through V̇ O2peak tests, strength tests through a variety of one-repetition max tests and body
composition through BIA. Significant improvements were observed in lift and carry (p=0.17),
weighted stair climb (p=.012), posterior leg reach (p=.014), thigh extension (p=.007) and
flexion (p=.027) strength and systolic blood pressure (p=.012). Favourable, but non-significant
(p>.05), effects on body composition were observed. No significant (p>0.05) change was seen
in bench press 1RM, handgrip strength or V̇ O2peak. This study showed that HIFT can provide
significant improvements in functional capacity and lower body strength. Participants in the
current study were already physically active, which may account for the lack of change in upper
body strength and cardiorespiratory fitness. No significant reductions were observed in any
variable, suggesting that HIFT is effective at maintaining and, in some cases, improving aspects
of fitness in physically active breast cancer survivors.