This resistance training protocol is significant because it can be applied in animal research to elucidate the effects of strength training on health. The main advantage of this method is that it can be applied for various strength training models and strength assessments. This technique provides an insight into physical fitness, specifically strength, and can be applied to study systemic diseases and the effect of treatments on muscle performance.
It allows for training and evaluating the strength of mice, but has a mandatory requirement which is the realization of sufficient acclimatization. Visual demonstration of this method is critical because the visualization of handling, training, and assessing the resistance of the mice is more meaningful than text. Demonstrating the procedure will be Doctor Cristina Tomas-Zapico and Doctor Manuel Fernandez Sanjurjo from Doctor Benjamin Fernandez-Garcia's laboratory.
To begin, carefully select animals for the study based on the characteristics of interest. Plan all issues related to training, particularly, the timetable, duration of the training period, and frequency of sessions, and draw a training table. Next, accustom the mice to stay in the resting area at the top of the ladder by leaving the animals in this area in groups of four with bedding from their cage for 15 minutes every day.
Teach the mice to climb up and knock down the ladder. For this, use a static ladder and place the mouse on a rung close to the top of the ladder from where they can see the resting area and instinctively go to it. Teach them progressively to climb up from 5 rungs the first day, to 10 rungs the following day, up to 15 rungs.
Next, use the same procedure with a dynamic ladder, first without movement, then with the ladder moving at 5.4 and 6.6 centimeters per second, and the mice climbing up for 2 minutes, completing 5 series. Next, prepare the following materials for the resistance exercise, weights, wire for holding weights, steel gator clip, and clinical adhesive tape. On the third day of acclimatization, cut a piece of the clinical adhesive tape and attach it around the mouse's tail to adapt it to carrying weights.
On the seventh day of acclimatization, insert small weights in the wire and hook the gator clip. Clamp the gator to the clinical tape attached to the mouse's tail and place the mouse on the ladder, Immediately after the mouse has climbed the required rungs, remove the clamp and allow the mouse to rest with the clinical tape on the tail but without the weight. Before performing incremental tests to assess maximal strength, perform a warmup session consisting of three series of 10 repetitions, 10 steps per repetition without external load.
Set the slope at 90 degrees for the first series, and after that at 85 degrees. Allow a rest period of 60 seconds between series. After attaching an external load of 10 grams on the mouse's tail, as demonstrated earlier, start the test with the slope set at 85 degrees and perform one series of 10 steps.
Remove the weight and allow a rest period of 120 seconds in the resting area. Then perform a successive series of 10 steps increasing the external load by five grams until exhaustion. Allow the 120 second resting period between series.
If a mouse fails to climb 10 steps with a particular weight load, allow for another attempt with the same load after 120 seconds of rest. If it fails again, record the weight load of the last completed series as the maximal weight load. If it succeeds in climbing with the load, continue the test with the next load.
To perform an incremental test with the dynamic ladder for assessing maximal strength, clip the appropriate weight on the clinical tape and start the test at 4.2 centimeters per second. Increase the speed by 1.2 centimeters per second every 60 seconds until exhaustion and record the time as result. To perform the maximal endurance resistance test with the static ladder after a warmup session with no weights, as demonstrated previously, clip the appropriate weight on the clinical tape placed around the tail of the mouse.
Then, keeping the ladder at an 85 degree slope, perform consecutive series of 10 steps until exhaustion with no resting time between each series and record the number of rungs climbed. To perform the maximal endurance resistance test with the dynamic ladder, set the slope at 85 degrees and speed at 4.2 centimeters per second. For warming up, perform three series of 100 steps without external load and allow rest period of 60 seconds between series.
After the warmup, allow a 120 second rest period before initiating the test. Then clip the gator with the external load, place the mouse on the running ladder, and start the stopwatch. The test ends when the mouse is no longer able to maintain the rate of ascent.
For resistance training with the static ladder, start the training session in the resting area and perform the warmup session without external load. Then clip the gator with the weight on the clinical tape and gently place the mouse 10 to 20 rungs below the resting place. Allow the mouse to grip the rung and climb to the resting area.
Repeat this process until the number of rungs in the series is completed. Remove the weight from the mouse tail and wait for 120 seconds until the next series. Increase the number of steps and the maximum weight load of the series throughout the training period following the training plan.
For resistance training with the dynamic ladder, after setting the slope to 85 degrees, close the door to the resting area and start the ladder at the desired speed. After a warmup procedure, when the mouse is in the resting area, clip the gator with the weight on the clinical tape. Alternatively, the weight can be attached when the mouse is on the ladder.
Then gently place the mouse at the top of the moving ladder with the weight on the tail and allow the mice to grip the rung and climb. When the number of rungs in this series is reached, the weights are removed and the door is opened so that the animal can go to the resting area. The rest time is 120 seconds before the next series.
Repeat this procedure until the training session is completed. The effect on resistance after six weeks of strength training on a dynamic ladder is shown here. The variation in maximal strength shows a significant increase after training in the strength and endurance resistance groups, while this parameter did not change in the control group.
Endurance resistance measured at the end of the training period was significantly higher in the endurance resistance group as compared to that in the strength and control groups. Proper acclimatization, including learning to climb and adapting to the clinical tape and weights is important. This procedure allows researchers to design various types of resistance training interventions.
Strength is relevant to human health and aging. Researchers can use these methods to explore the effects of exercise and pharmacological interventions on resistance.
