Short Session High Intensity Interval Training and Treadmill Assessment in Aged Mice

Summary

Short session (≤10 min) high intensity interval training (HIIT) is emerging as an alternative to longer exercise modalities, yet the shorter variants are rarely modeled in animal studies. Here, we describe a 10 min, 3 day a week, uphill treadmill HIIT protocol that enhances physical performance in male and female aged mice.

Abstract

High intensity interval training (HIIT) is emerging as a therapeutic approach to prevent, delay, or ameliorate frailty. In particular short session HIIT, with regimens less than or equal to 10 min is of particular interest as several human studies feature routines as short as a few minutes a couple times a week. However, there is a paucity of animal studies that model the impacts of short session HIIT. Here, we describe a methodology for an individually tailored and progressive short session HIIT regimen of 10 min given 3 days a week for aged mice using an inclined treadmill. Our methodology also includes protocols for treadmill assessment. Mice are initially acclimatized to the treadmill and then given baseline flat and uphill treadmill assessments. Exercise sessions begin with a 3 min warm-up, then three intervals of 1 min at a fast pace, followed by 1 min at an active recovery pace. Following these intervals, the mice are given a final segment that starts at the fast pace and accelerates for 1 min. The HIIT protocol is individually tailored as the speed and intensity for each mouse are determined based upon initial anaerobic assessment scores. Additionally, we detail the conditions for increasing or decreasing the intensity for individual mice depending on performance. Finally, intensity is increased for all mice every two weeks. We previously reported in this protocol enhanced physical performance in aged male mice and here show it also increases treadmill performance in aged female mice. Advantages of our protocol include low administration time (about 15 min per 6 mice, 3 days a week), strategy for individualizing for mice to better model prescribed exercise, and a modular design that allows for the addition or removal of the number and length of intervals to titrate exercise benefits.

Introduction

Regular exercise is effective at preventing or delaying many age-associated diseases such as sarcopenia and frailty^1,2,3,4. However, less than 15% of those 65 and older meet recommendations of 150 min a week of moderate intensity exercise plus strength
training^5,6. As the lack of time and lengthy sessions are common barriers to exercise, high intensity interval training (HIIT) is emerging as an alternative to traditional regimens. HIIT features multiple short bursts of intense ....

Protocol

All studies and experimental protocols were approved by and in compliance with guidelines of the University at Buffalo and VA Western New York Animal Care and Use Committees.

1. Experiment Setup and General Advice

NOTE: A total of twenty-four female mice on a C57BL/6J background were used in this protocol starting at 23 months of age. The mice carried a conditional SIRT^{loxp-exon4-loxp} mutation²⁹, however, this was not induced in this experiment.

1. Ensure that mice receive permanent identifiers such as ear tags, RFID chips, or tail tattoos.

Results

A total of twenty-five female mice were bred and aged in house. The C57BL/6J background mice carried a SIRT1^{loxp-exon4-loxp} mutation²⁹; however, this conditional knockout was not induced and therefore all mice exhibited full length Sirtuin1 (data not shown). At 24 months of age, mice were assessed for treadmill endurance and uphill sprint capacity prior to and after the administration of two months of HIIT exercise (n = 14), or remaining cage se.......

Discussion

Benefits from short sessions are a key aspect of high intensity interval training that captures scientific and public interest. However, animal studies rarely investigate HIIT regimens that are 10 min or less. Here, we describe a protocol for a 10 min short session HIIT uphill treadmill exercise regimen that enhanced treadmill performance in aged female mice and which we previously have shown to increase physical performance in aged male mice¹⁷. A strength of our protocol is that in addition to th.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Exer-3/6 Open Treadmill w/ Shock, Detection, auto-calibration and PC Interface/Software	Columbus Instruments	1055-SDRM	The Columbus Instruments 3/6 treadmill allow up to 6 mice or 3 rats simultaneously. The device comes with controllers to allow manual control of treadmill belt speed and shock intensity, or connections to a computer and software to run and control these elements.
Bleach	Varies	Varies	0.25-0.5% Bleach solution (V/V) is used to clean the treadmill belt between sessions
Ethanol	Varies	Varies	70% ethanol solution (V/V) can alternatively be used to clean treadmill belt between runs and sesions.
Make-up Brush (large)	Varies	Varies	A make-up brush provides a soft surface and ample length to motivate mice to continue exercise.