2.3.1

Whole-body strength training with HML and assessment of MVC

The Huber Motion Lab (LPG Systems, France) is an oscillating platform with 2 large handles mounted on a movable column. Several feet and hand positions are marked on the platform and handles, respectively ( Fig. 1 ). HML exercises consist of adopting specific positions, defined as a combination of various foot and hand positions, and developing low-high force levels against the handles. These actions require the synergistic activation of various muscle groups of the lower limbs, trunk and upper limbs. The handles are equipped with strain gauges, and feedback about the force developed is provided to users. Additionally, an interactive interface, shown as a target, informs the subject about their ability to maintain the required force level. This “game-like” control panel is intended to increase the user’s motivation to practice and adhere to the HML training program .

The Huber Motion Lab, an oscillating platform with 2 large handles mounted on a movable column. Several feet and hand positions are marked on the platform and handles, respectively.

MVC was measured in standardized positions before each subsequent position ( Fig. 1 ). Patients were asked to exert maximal isometric pushing and pulling forces (i.e., opposite actions with the 2 hands on the handles). For each position, pulling and pushing forces were recorded by the strain gauges on the handles. Patients performed two 6 s MVCs for each position. A third trial was performed when the difference in results between the first 2 trials was > 5%. Verbal encouragement and visual feedback about the force developed were provided to patients during each MVC. The greatest mean force produced over the 6 s period was retained as the MVC value for each action (i.e., pulling and pushing force).

2.3.2

HML sessions

The velocity/inclination of the plate (rotation) was set at 30/30 (See HML instructions manual). Both exercises consisted of 6 exercise blocks in different postures. The positions are presented in Fig. 1 . Each block consisted of 8 contractions of 6 s alternating with 10 s of passive recovery, repeated twice. The total duration of the session, which included a 3-min warm-up, 10 min of MVC assessment, 27 min of exercise and 5-min recovery, was 45 min. The intensity of isometric contraction was set at 70% of the MVC . All patients performed a familiarization session in the days before the protocol. To validate and start the protocol, patients had to validate a coordination score corresponding to a minimum of 60% . Because the MVC was calculated at each session, the exercise intensity was automatically adapted to enable progression.

2.3.3

TST sessions and assessment of MVC

TST sessions involved a circuit training including 6 different machines: leg press, chest press, vertical traction (shoulder press), low row (working back), pectoral (butterfly) and leg extension. Movements allowed for dynamically working the same muscle groups as with the HML. According to the guidelines for resistance training in cardiac rehabilitation, we set the intensity at 60% of MVC. At each position, patients were asked to repeat 3 series of 12 repetitions. With TST, the MVC was calculated by using the one-repetition maximum test (1-RM) on each machine at the beginning of each week during the program.

2.4.1

Anthropometric variables and body composition

The formula used for calculating BMI was weight in kilograms (kg) divided by height in meters (m) squared. The waist circumference was determined by use of a measuring tape (e.g., K & E type) placed halfway between the lower part of the ribcage and the hipbone . Body composition was measured by bioelectrical impedance by using the BODYSTAT 1500 (Bodystat Ltd., British Isles).

2.4.2

Endothelial function

Reactive hyperemia index (RHI), a measure of endothelial function, was assessed by using the EndoPAT 2000 device (Itamar Medical, Israel). This measurement was calculated by using a computerised automated algorithm provided with the accompanying software (v3.1.2) and performed according to the manufacturer’s instructions. Briefly, patients were in a supine position for a minimum of 20 min before measurement in a quiet, temperature-controlled (21–24 °C) room with dimmed lights. Patients were asked to remain as still as possible and silent during the entire measurement period. Each recording consisted of 5 min baseline measurement, 5 min occlusion measurement, and 5 min post-occlusion measurement (hyperemic period). Occlusion of the brachial artery involved the nondominant upper arm. The occlusion pressure was at least 60 mmHg above the systolic blood pressure (BP) (minimally 200 mmHg, and maximally 300 mmHg). The natural logarithmic scaled RHI (L_RHI) was calculated from the ratio between the digital pulse volume during RH and at baseline .

2.4.3

MVC

Patients were seated on the extremity of a bench. The bench was raised to ensure that the feet did not contact the floor. The knee joint tested was set in the gravity-neutral position. The thigh was strapped to the bench. The MVC of the quadriceps was tested by using a strain gauge system, the Meas FN3148 Load cell with mechanical stops (Measurement Specialities, Aliso Viejo, CA). This strain gauge has an accuracy of 0.05% and range of 0–2000 N. It is quality certified. Extremities of the strain gauges were attached to steel cables by hooks. One of the steel cables was attached to a bench hook and the other end to the ankle by use of a strap. The strain gauge and strap were set perpendicular to the line of force. Analogic strain gauge readings were transferred to software on a computer via a sensor interface. Once installed in the apparatus, patients, with their arms crossed over their chest, were asked to extend their knee as strongly as possible against the resistance of the cable steel for a contraction period with a 1 s transition period and a 4- to 5 s plateau that is supposed to be sufficient to achieve maximal isometric contraction. The time force motion was numerically registered and visualized during extension. The peak force was identified on the curve according to the reliability of the decision by 2 assessors. Three trials separated by 1-min rest intervals were proposed. The best peak force between the trials was recorded as the maximal force contraction of the quadriceps for the study. The same method was used in the chest press position to measure the strength of the upper body.

2.4.4

Cardiopulmonary stress test

The peak power output (PPO) was determined by a test on an ergocycle with electromagnetic braking (Ergometrics 900, Ergoline, Germany). The PPO corresponds to the power reached at the last threshold of the test. The initial power was set to 30 W with an increment of 15 W/min. This progressive increase test was performed with continuous 12-lead ECG monitoring. Blood pressure was checked every 2 min during the stress test and during 6-min recovery (3-min active recovery and 3-min passive recovery). The Borg scale was used to evaluate the rate of perceived exertion from 6 to 20 . The stress test was stopped when the patient was not able to maintain the required power or when the score of perceived exertion was 15–17/20, in case of severe angina pectoris (> 5/10), severe arrhythmia, decrease in BP >10 mmHg or ST-segment elevation > 2 mm . Metabolic equivalents (METs) were calculated from the Watts obtained at PPO, considering that 1 litre of O ₂ = 5.05 Kcal and 1 MET = 3.5 mL O ₂ /Kg body weight/min.

2.4.5

Quality of life

Health-related quality of life was measured by using the French version of the Medical Outcomes Study Short Form 36 (SF-36) . The SF-36 includes 36 questions grouped into 8 categories corresponding to physical activity, limits due to the physical state, physical pain, self-perceived health, vitality, relationships with others, psychological health and limits related to the psychological state. For each category, the sum of the item scores was translated linearly to a scale from 0 (maximal exhaustion) to 100 (no exhaustion). Physical activity, physical pain and limits related to the physical state reflect the physical component score (PCS), and self-perceived health, vitality, psychological health, relationships to others and limits related to the psychological state reflect the mental component score (MCS). PCS and MCS were computed by using equations developed by Ware and Kosinski .

2.4.6

Sleep quality

The Pittsburgh Sleep Quality Index (PSQI) assesses sleep quality during the previous month and differentiates “good” and “bad” sleepers . Sleep quality is a complex phenomenon that implies several dimensions, each analysed by the PSQI. This questionnaire includes 19 self-assessment questions and 5 questions asked of the life partner, spouse or roommate (as appropriate). The questions correspond to 7 components: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. Only the self-assessment questions are included in the final score. Scores for the 7 components add to a final global score from 0 to 21 points, 0 meaning no sleep difficulty and 21 major difficulties. A global PSQI score > 5 suggests significant sleep disturbances.

2.3.1

Whole-body strength training with HML and assessment of MVC

The Huber Motion Lab (LPG Systems, France) is an oscillating platform with 2 large handles mounted on a movable column. Several feet and hand positions are marked on the platform and handles, respectively ( Fig. 1 ). HML exercises consist of adopting specific positions, defined as a combination of various foot and hand positions, and developing low-high force levels against the handles. These actions require the synergistic activation of various muscle groups of the lower limbs, trunk and upper limbs. The handles are equipped with strain gauges, and feedback about the force developed is provided to users. Additionally, an interactive interface, shown as a target, informs the subject about their ability to maintain the required force level. This “game-like” control panel is intended to increase the user’s motivation to practice and adhere to the HML training program .

The Huber Motion Lab, an oscillating platform with 2 large handles mounted on a movable column. Several feet and hand positions are marked on the platform and handles, respectively.

MVC was measured in standardized positions before each subsequent position ( Fig. 1 ). Patients were asked to exert maximal isometric pushing and pulling forces (i.e., opposite actions with the 2 hands on the handles). For each position, pulling and pushing forces were recorded by the strain gauges on the handles. Patients performed two 6 s MVCs for each position. A third trial was performed when the difference in results between the first 2 trials was > 5%. Verbal encouragement and visual feedback about the force developed were provided to patients during each MVC. The greatest mean force produced over the 6 s period was retained as the MVC value for each action (i.e., pulling and pushing force).

2.3.2

HML sessions

The velocity/inclination of the plate (rotation) was set at 30/30 (See HML instructions manual). Both exercises consisted of 6 exercise blocks in different postures. The positions are presented in Fig. 1 . Each block consisted of 8 contractions of 6 s alternating with 10 s of passive recovery, repeated twice. The total duration of the session, which included a 3-min warm-up, 10 min of MVC assessment, 27 min of exercise and 5-min recovery, was 45 min. The intensity of isometric contraction was set at 70% of the MVC . All patients performed a familiarization session in the days before the protocol. To validate and start the protocol, patients had to validate a coordination score corresponding to a minimum of 60% . Because the MVC was calculated at each session, the exercise intensity was automatically adapted to enable progression.

2.3.3

TST sessions and assessment of MVC

TST sessions involved a circuit training including 6 different machines: leg press, chest press, vertical traction (shoulder press), low row (working back), pectoral (butterfly) and leg extension. Movements allowed for dynamically working the same muscle groups as with the HML. According to the guidelines for resistance training in cardiac rehabilitation, we set the intensity at 60% of MVC. At each position, patients were asked to repeat 3 series of 12 repetitions. With TST, the MVC was calculated by using the one-repetition maximum test (1-RM) on each machine at the beginning of each week during the program.

2.4.1

Anthropometric variables and body composition

The formula used for calculating BMI was weight in kilograms (kg) divided by height in meters (m) squared. The waist circumference was determined by use of a measuring tape (e.g., K & E type) placed halfway between the lower part of the ribcage and the hipbone . Body composition was measured by bioelectrical impedance by using the BODYSTAT 1500 (Bodystat Ltd., British Isles).

2.4.2

Endothelial function

Reactive hyperemia index (RHI), a measure of endothelial function, was assessed by using the EndoPAT 2000 device (Itamar Medical, Israel). This measurement was calculated by using a computerised automated algorithm provided with the accompanying software (v3.1.2) and performed according to the manufacturer’s instructions. Briefly, patients were in a supine position for a minimum of 20 min before measurement in a quiet, temperature-controlled (21–24 °C) room with dimmed lights. Patients were asked to remain as still as possible and silent during the entire measurement period. Each recording consisted of 5 min baseline measurement, 5 min occlusion measurement, and 5 min post-occlusion measurement (hyperemic period). Occlusion of the brachial artery involved the nondominant upper arm. The occlusion pressure was at least 60 mmHg above the systolic blood pressure (BP) (minimally 200 mmHg, and maximally 300 mmHg). The natural logarithmic scaled RHI (L_RHI) was calculated from the ratio between the digital pulse volume during RH and at baseline .

2.4.3

MVC

Patients were seated on the extremity of a bench. The bench was raised to ensure that the feet did not contact the floor. The knee joint tested was set in the gravity-neutral position. The thigh was strapped to the bench. The MVC of the quadriceps was tested by using a strain gauge system, the Meas FN3148 Load cell with mechanical stops (Measurement Specialities, Aliso Viejo, CA). This strain gauge has an accuracy of 0.05% and range of 0–2000 N. It is quality certified. Extremities of the strain gauges were attached to steel cables by hooks. One of the steel cables was attached to a bench hook and the other end to the ankle by use of a strap. The strain gauge and strap were set perpendicular to the line of force. Analogic strain gauge readings were transferred to software on a computer via a sensor interface. Once installed in the apparatus, patients, with their arms crossed over their chest, were asked to extend their knee as strongly as possible against the resistance of the cable steel for a contraction period with a 1 s transition period and a 4- to 5 s plateau that is supposed to be sufficient to achieve maximal isometric contraction. The time force motion was numerically registered and visualized during extension. The peak force was identified on the curve according to the reliability of the decision by 2 assessors. Three trials separated by 1-min rest intervals were proposed. The best peak force between the trials was recorded as the maximal force contraction of the quadriceps for the study. The same method was used in the chest press position to measure the strength of the upper body.

2.4.4

Cardiopulmonary stress test

The peak power output (PPO) was determined by a test on an ergocycle with electromagnetic braking (Ergometrics 900, Ergoline, Germany). The PPO corresponds to the power reached at the last threshold of the test. The initial power was set to 30 W with an increment of 15 W/min. This progressive increase test was performed with continuous 12-lead ECG monitoring. Blood pressure was checked every 2 min during the stress test and during 6-min recovery (3-min active recovery and 3-min passive recovery). The Borg scale was used to evaluate the rate of perceived exertion from 6 to 20 . The stress test was stopped when the patient was not able to maintain the required power or when the score of perceived exertion was 15–17/20, in case of severe angina pectoris (> 5/10), severe arrhythmia, decrease in BP >10 mmHg or ST-segment elevation > 2 mm . Metabolic equivalents (METs) were calculated from the Watts obtained at PPO, considering that 1 litre of O ₂ = 5.05 Kcal and 1 MET = 3.5 mL O ₂ /Kg body weight/min.

2.4.5

Quality of life

Health-related quality of life was measured by using the French version of the Medical Outcomes Study Short Form 36 (SF-36) . The SF-36 includes 36 questions grouped into 8 categories corresponding to physical activity, limits due to the physical state, physical pain, self-perceived health, vitality, relationships with others, psychological health and limits related to the psychological state. For each category, the sum of the item scores was translated linearly to a scale from 0 (maximal exhaustion) to 100 (no exhaustion). Physical activity, physical pain and limits related to the physical state reflect the physical component score (PCS), and self-perceived health, vitality, psychological health, relationships to others and limits related to the psychological state reflect the mental component score (MCS). PCS and MCS were computed by using equations developed by Ware and Kosinski .

2.4.6

Sleep quality

The Pittsburgh Sleep Quality Index (PSQI) assesses sleep quality during the previous month and differentiates “good” and “bad” sleepers . Sleep quality is a complex phenomenon that implies several dimensions, each analysed by the PSQI. This questionnaire includes 19 self-assessment questions and 5 questions asked of the life partner, spouse or roommate (as appropriate). The questions correspond to 7 components: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. Only the self-assessment questions are included in the final score. Scores for the 7 components add to a final global score from 0 to 21 points, 0 meaning no sleep difficulty and 21 major difficulties. A global PSQI score > 5 suggests significant sleep disturbances.