Exercise interventions for patients with type 1 diabetes mellitus: A narrative review with practical recommendations

Table 1 Evaluation protocols in type 1 diabetes mellitus exercise programming

Parameter	Measures	Comments
Aerobic fitness
Incremental test	Workload and steady-state HR to predict VO2peak; RPE	Treadmill or cyclo-ergometer; Gas collection system and HR monitor necessary. Begin with unloaded warm-up
6-min walking test	Total distance walked, HR, RPE, BP	HR and BP monitor necessary
Muscular strength/power
Indirect repetitions maximum testing	Maximal weight lifted for < 10 repetitions	Use machines. Remind patients to exhale on concentric action and avoid holding their breath
Force-Velocity profile	Execution velocity at a given load	Encoder necessary
Timed up and go test	Time to stand from a chair, walk a 3-m round trip, and sit back down on the same chair	Results correlate with gait speed, balance, functional level, the ability to go out
30-s sit to stand test	Number of times patient comes to a full stand with arms crossing a standard size chair in 30 s	A functional measure of lower limb strength, power, and muscle endurance
Flexibility/mobility
Goniometry	Range of motion	Focus on flexibility of hamstrings, hip flexors, ankle plantar flexors, shoulder adductors, and internal rotators
WBLT	Ankle dorsiflexion	No footwear; no equipment
Psychological well-being
SF-36	Quality of life	Eight-domain profile of functional health and well-being scores
PSQI	Sleep quality	Seven-domain profile of sleep quality and related disorders

BP: Blood pressure; HR: Heart rate; PSQI: Pittsburgh Sleep Quality Index; RPE: Rating of perceived exertion; SF-36: Short Form Health Survey-36; WBLT: Weight-bearing lunge test.

Table 2 Practical recommendations for exercise prescription in type 1diabetes mellitus patients

Aerobic exercise1	HIIT	Resistance exercise
Exercise intensity: Start with an intensity of 40%-70% of VO2max and gradually increase to 60%-80% of maximum heart rate. RPE of 11-13 is recommended	Exercise intensity: > 90 VO2max, 90%-95% of maximum heart rate, and an RPE of 15-18	Exercise intensity: 50%-75% 1RM, RPE of 7-8. Participants should perform the exercises as fast as possible during the concentric phase (maximal movement intention). A 20% loss in concentric velocity among the repetitions of each set may be established as a limit in the volume at the given intensity
Exercise volume: 10-40 min duration is suggested. At first, it can be divided into three bouts of 10-12 min per session	Exercise volume: 12-20 sets. Bouts of 30 s interspersed by 60 s rest (ratio 1:2)	Exercise volume: 1-3 sets of 10-15 reps; 8-10 exercises of large muscles are essential
Exercise mode: Low impact cyclo-ergometer, arm ergometer, arm-leg ergometer, aquatic exercise, treadmill walking, rowing, and running	Exercise mode: Aerobic exercises such as cycling, running, rowing, etc. First, HIIT must be performed in low impact conditions, such as cyclo-ergometer or aquatic environment, aiming for at least a total of 4-min at high intensity	Exercise mode: Prioritize lower limb exercises and multi-joint exercises. Exercise velocity must be initially moderated (1-2 s concentric, 1-2 s eccentric)
Training frequency: 1-3 sessions per week; as per patient tolerance	Training frequency: 1-3 sessions per week	Training frequency: 2-3 sessions per week
Progression: During the first 1-4 mo, progression should be achieved by increasing the duration or frequency of exercise sessions. After this time, test whether higher intensity in continuous exercise is tolerated	Progression: Increase total training volume gradually, then increase the density by reducing active rest intervals or increasing the length of the HIIT bouts, as per patient tolerance	Progression: Begin with weight-stack machines, elastic bands, and weightbearing exercises. Increase load and progress to more technically demanding exercises. An exercise intensity of resistance can be securely added by 2% to 5% when 15 repetitions can be properly performed in successive training sessions

¹When the insulin-carbohydrate ratio is cautiously established. 1RM: One-repetition maximum; HIIT: High-intensity interval training; RPE: Rating of perceived exertion.