**2.1. Acute study**

Ten males (23±3 years, 1.79±0.06m, 73.4±8.4Kg) gave written informed consent to take part in the study. All procedures and experimental protocols were approved by the Ethics Committee at the Manchester Metropolitan University. Exclusion criteria for participation in the study were the presence of any known musculoskeletal, neurological, inflammatory or metabolic disorders or injury. Participants were physically active, involved in recreational activities such as team sports, and had either never taken part in intensive (more than two hours a week) lower limb resistance training or not within the previous 12 months. Participants attended the laboratory for a total of five occasions. The first visit included demonstration of the appropriate squat technique for a standard barbell back squat, and familiarisation of the exercise protocol and testing equipment. The following week participants returned on four occasions, firstly to record their one repetition maximum over each range-of-motion, which was defined as the maximum amount of external weight (Kg) that could be lifted in a controlled manner through the entire range-of-motion, and their MVC on an isokinetic dynamometer ( Cybex, Phoenix Healthcare Products, UK) at 50o and 90o of knee flexion. The time-line of the sessions was as follows: Day 1; 1RM & MVC, Day 2; Rest, Day 3; Protocol 1, Day 4; Rest, Day 5; Protocol 2, Day

configuration with an inter-electrode distance of 20 mm. The electrodes were placed at 50% of femur length and 50% of muscle width of the *Vastus Lateralis* muscle (VL). The reference electrode (Blue sensor L, Ambu, Denmark) was placed on the lateral tibial condyle. The raw EMG signal was amplified and bandpass filtered between 10-500 Hz (MP100, Biopac Systems Inc., USA) with a 50Hz notch filter, and sampled at 2000 Hz. All EMG and torque signals were displayed in real time in AcqKnowledge software (Biopac Systems Inc., USA) via a PC (iMac, Apple Inc., USA). The root mean square (RMS) EMG activity was averaged for a 500ms period

How Deep Should You Squat to Maximise a Holistic Training Response?...

http://dx.doi.org/10.5772/56386

159

which coincided with the plateau of peak torque of all analysed muscle contractions.

recorded.

muscle length 0-50o

**2.2. Chronic resistance exercise program study**

muscle length; 5 males, 6 females 40-90o

weeks of detraining (week 12).

range of motion, 6 males, 5 females 0-90o

*Oxygen Consumption (VO*2*)*; Gases for VO2 consumption were collected using standard Douglas Bag techniques. Prior to the beginning of each set of exercise, a clip was placed on the nose of the participant, the Douglas bag mouthpiece was inserted into the mouth and the valve on an empty bag subsequently opened. After the set of exercise was completed, 30 seconds were allowed to elapse before the valves were closed. This was to allow for any excess post-exercise oxygen consumption during the immediate recovery period. A separate Douglas bag was used for every set of exercise completed. Each bag was analysed using a gas analysis program (Servomex 5200 Multiuse, Crowborough, UK) and was used to calculate the FECO2 and FEO2 percentages. For these calculation, the data from Gas which had been evacuated for 60 s with a flow rate of 2.1 L/min, the total gas volume which was obtained using a Harvard Dry Gas vacuum (NB. the flow rate (2.1 L) was added to the final figure to give the VE stpd (L/ min-1)), the time period in which the Douglas bag was open (secs), load (kg) and subjects' heart rate were all inserted into the gas analysis programme. The VO2 (ml/kg-1/min-1) was also

*Heart rate & Blood Pressure*; Heart rate and blood pressure were recorded at rest in the supine position before the onset of exercise using a standard heart rate monitor (Polar, UK) and electronic blood pressure monitoring device (Panasonic Diagnostec, UK). These parameters were also measured immediately post-exercise, after every set of exercise. Rate of perceived exertion (RPE) was also recorded following the conclusion of each individual set of exercise.

Thirty two activity-matched participants were allocated to a training group – SL (shorter

participants (6 males and 4 females; 23±2.4 years, 1.76±0.09m, 77.9±13.1Kg) were assigned to the non-training control group (Con), and continued their normal habitual activity throughout the study period. A One-way ANOVA revealed that the population was homogeneous at baseline for all parameters of interest (P>0.05). All groups were assessed at baseline (week 0), post-training (week 8), after two weeks of detraining (week 10) and following a further two

*Electromyography;* Preparation of EMG site, measurement and assessment of EMG were as described in the previous section. In addition to these measurements, EMG of the biceps

; 6 males, 4 females; aged 19±2.2 years, 1.76±0.15m, 75.7±13.2Kg), LL (longer

; 21±3.4 years, 1.75±0.14m, 74.9±14.7Kg) or LX (Whole

;19.2±2.6 years, 1.71±0.11m, 73.8±14.9Kg). Ten

**Figure 1.** Diagram showing the various knee-joint ranges-of-motion used in the training protocols with a view to de‐ scribe both acute and chronic training responses

6; Rest, Day 7; Protocol 3. During each of the resistance exercise protocol days, the participants were randomly allocated to perform the resistance exercise session of one of the three desig‐ nated ranges-of-motion. During each of the resistance exercise sessions, all acute variables (EMG, VO2, heart rate, blood pressure) were measured.

*Exercise Protocols*; Each exercise protocol involved performing exercise over one of three ranges-of-motion (Figure 1). The three ranges-of-motion were; 0-50o knee flexion (shorter muscle lengths, SL), 40-90o knee flexion (longer muscle lengths, LL) and 0-90o knee flexion (complete range-of-motion incorporating shorter and longer muscle lengths, LX). A goniom‐ eter was attached to the knee joint centre of rotation, from which the investigator confirmed each angle was met during exercise performance. Each exercise session required participants to perform one set of five repetitions back squats at an absolute load of 20Kg, 40Kg and finally 60Kg. Sets were interspersed by two minutes of recovery. Following a further ten minutes rest, each participant performed a further set of five back squats at 40%, 60% and 80% 1RM, interspersed by two minutes of rest.

*Electromyography;* A pair of self-adhesive Ag-AgCl electrodes 15 mm in diameter (Neuroline 720, Ambu, Denmark), were placed on clean, shaved, and previously abraded skin, in a bipolar configuration with an inter-electrode distance of 20 mm. The electrodes were placed at 50% of femur length and 50% of muscle width of the *Vastus Lateralis* muscle (VL). The reference electrode (Blue sensor L, Ambu, Denmark) was placed on the lateral tibial condyle. The raw EMG signal was amplified and bandpass filtered between 10-500 Hz (MP100, Biopac Systems Inc., USA) with a 50Hz notch filter, and sampled at 2000 Hz. All EMG and torque signals were displayed in real time in AcqKnowledge software (Biopac Systems Inc., USA) via a PC (iMac, Apple Inc., USA). The root mean square (RMS) EMG activity was averaged for a 500ms period which coincided with the plateau of peak torque of all analysed muscle contractions.

*Oxygen Consumption (VO*2*)*; Gases for VO2 consumption were collected using standard Douglas Bag techniques. Prior to the beginning of each set of exercise, a clip was placed on the nose of the participant, the Douglas bag mouthpiece was inserted into the mouth and the valve on an empty bag subsequently opened. After the set of exercise was completed, 30 seconds were allowed to elapse before the valves were closed. This was to allow for any excess post-exercise oxygen consumption during the immediate recovery period. A separate Douglas bag was used for every set of exercise completed. Each bag was analysed using a gas analysis program (Servomex 5200 Multiuse, Crowborough, UK) and was used to calculate the FECO2 and FEO2 percentages. For these calculation, the data from Gas which had been evacuated for 60 s with a flow rate of 2.1 L/min, the total gas volume which was obtained using a Harvard Dry Gas vacuum (NB. the flow rate (2.1 L) was added to the final figure to give the VE stpd (L/ min-1)), the time period in which the Douglas bag was open (secs), load (kg) and subjects' heart rate were all inserted into the gas analysis programme. The VO2 (ml/kg-1/min-1) was also recorded.

*Heart rate & Blood Pressure*; Heart rate and blood pressure were recorded at rest in the supine position before the onset of exercise using a standard heart rate monitor (Polar, UK) and electronic blood pressure monitoring device (Panasonic Diagnostec, UK). These parameters were also measured immediately post-exercise, after every set of exercise. Rate of perceived exertion (RPE) was also recorded following the conclusion of each individual set of exercise.

## **2.2. Chronic resistance exercise program study**

6; Rest, Day 7; Protocol 3. During each of the resistance exercise protocol days, the participants were randomly allocated to perform the resistance exercise session of one of the three desig‐ nated ranges-of-motion. During each of the resistance exercise sessions, all acute variables

**Figure 1.** Diagram showing the various knee-joint ranges-of-motion used in the training protocols with a view to de‐

*Exercise Protocols*; Each exercise protocol involved performing exercise over one of three ranges-of-motion (Figure 1). The three ranges-of-motion were; 0-50o knee flexion (shorter

(complete range-of-motion incorporating shorter and longer muscle lengths, LX). A goniom‐ eter was attached to the knee joint centre of rotation, from which the investigator confirmed each angle was met during exercise performance. Each exercise session required participants to perform one set of five repetitions back squats at an absolute load of 20Kg, 40Kg and finally 60Kg. Sets were interspersed by two minutes of recovery. Following a further ten minutes rest, each participant performed a further set of five back squats at 40%, 60% and 80% 1RM,

*Electromyography;* A pair of self-adhesive Ag-AgCl electrodes 15 mm in diameter (Neuroline 720, Ambu, Denmark), were placed on clean, shaved, and previously abraded skin, in a bipolar

knee flexion (longer muscle lengths, LL) and 0-90o

knee flexion

(EMG, VO2, heart rate, blood pressure) were measured.

muscle lengths, SL), 40-90o

scribe both acute and chronic training responses

158 Electrodiagnosis in New Frontiers of Clinical Research

interspersed by two minutes of rest.

Thirty two activity-matched participants were allocated to a training group – SL (shorter muscle length 0-50o ; 6 males, 4 females; aged 19±2.2 years, 1.76±0.15m, 75.7±13.2Kg), LL (longer muscle length; 5 males, 6 females 40-90o ; 21±3.4 years, 1.75±0.14m, 74.9±14.7Kg) or LX (Whole range of motion, 6 males, 5 females 0-90o ;19.2±2.6 years, 1.71±0.11m, 73.8±14.9Kg). Ten participants (6 males and 4 females; 23±2.4 years, 1.76±0.09m, 77.9±13.1Kg) were assigned to the non-training control group (Con), and continued their normal habitual activity throughout the study period. A One-way ANOVA revealed that the population was homogeneous at baseline for all parameters of interest (P>0.05). All groups were assessed at baseline (week 0), post-training (week 8), after two weeks of detraining (week 10) and following a further two weeks of detraining (week 12).

*Electromyography;* Preparation of EMG site, measurement and assessment of EMG were as described in the previous section. In addition to these measurements, EMG of the biceps femoris was also recorded during graded maximal contractions in order to assess antagonist muscle co-activation.

*Resistance Training Program (RT)*; RT was carried out 3 days per week for 8 weeks and ceased during the 4 week detraining period. RT included performing 3-4 sets of 8-12 reps (depending on the stage of the training program) of exercises designed to overload the knee extensors muscle group. Exercises included the barbell back squat, leg extension, leg press, Bulgarian split squat, and forward lunge. 1RMs were assessed and recorded every two weeks to progress the exercise loads.

*Muscle size measurements*; VL muscle widths were measured using B-mode ultrasonography (AU5, Esaote Biomedica, Italy) at 25%, 50% and 75% of femur length. The ultrasound probe was held in the transverse plane and used to locate the borders of either side of the VL muscle. Each of these junctures was marked on the skin and the distance between them measured. In addition, at each of the aforementioned sites, thigh girths were also measured using standard anthropometric techniques. All data is presented as mean ± standard deviation (S.D.).

*Muscle strength measurements*; Throughout the training program, 1RM of the knee extensors systematically monitored on a knee extension machine (Technogym, Bracknell, UK).
