The Effects of Unilateral and Bilateral Battle Rope Exercise on the Lower Extremity Joint Force: A Pilot Study

The battle rope exercise recently has increased its popularity due to cross fit gyms implementing it into the workout programs. Individuals use this workout to strengthen their upper body, however it is unknown how different modalities of using the battle ropes affects the lower extremity joint force required to stabilize the body. PURPOSE: To examine the effects of unilateral and bilateral battle ropes exercises on lower extremity joint force. METHODS: Subjects performed four bilateral battle rope trials and four unilateral battle rope trials. The trials consisted of twenty seconds of continuous activity with three minutes of rest in between during a single visit to the lab. Lower extremity joints were tracked using a Qualisys motion capture system and Bertec force platforms. Joint force data (normalized to body mass) and ground reaction force (reported in Newtons, both in the medial-lateral axis) were analyzed in the down phase of the movement (from peak rope height to the bottom of the motion). RESULTS: There was decreased lateral force in the hip joint during the bilateral exercise for the left hip (0.601BM) and the right hip (0.586BM) compared to the unilateral (0.803BM and 0.614BM, respectively). However, the knee and ankle showed decreased lateral force during the unilateral exercise (0.376BM and 0.200BM for the left and right knee, respectively and 0.829BM and 1.052BM for the left and right ankle respectively) compared to the bilateral exercise (0.569BM and 0.336BM for the left and right knee, respectively and 1.047BM and 1.145BM for the left and right ankle, respectively). The bilateral exercise showed increased medially-directed forces in the right limb (133.4N) and left limb (148.7N) -compared to the unilateral (109.3N and 110.1N, respectively). CONCLUSION: The results show a discrepancy in terms of medial-lateral joint force. The unilateral exercise shows increased lateral stress on the hip joints while the bilateral shows an increased lateral stress on the ankle and knee. During unilateral exercises, the non-active side (side without the moving arm) hip and knee show increased lateral forces while the active-side ankle shows increased lateral forces. Lower extremity joint position should be considered when using these activities due to their impact on joint force experienced in the lower extremities

The Effect of Neuropriming and Focus of Attention on Amateur Standing Long Jump Performance

International Journal of Exercise Science 15(1): 1472-1480, 2022. Non-invasive brain stimulation has been prominent in recent neurophysiology research. The use of brain stimulation has not been examined in combination with the focus of attention paradigm, an established motor control tool. Therefore, the purpose of this study was to examine the effects of both brain stimulation and focus of attention on the outcome performance, peak force, lower extremity joint kinematics, and projection angle of a standing long jump. Forty-one participants were assigned to either the brain stimulation group or placebo group via a counterbalance design based on leg length and jump distance. Participants were only accepted if they had not previously trained in the standing long jump. On a second day, participants performed a standing long jump under control, external, and internal attentional foci after having undergone either a single session of brain stimulation or a placebo warm-up. Five total jumps were performed: one baseline jump followed by two for each attentional focus condition. The results indicated that an external focus of attention and control conditions created a reduced projection angle compared to an internal focus of attention and that brain stimulation did not have any effects on the performance of a standing long jump after a single session. There were no changes evident between hip, knee, and ankle joint angles, force production, or jump distance between any of the conditions or groups

Wearing Knee Sleeves During Back Squats Does Not Improve Mass Lifted or Affect Knee Biomechanics

Purpose:Knee sleeves have become widely popular in the exercise realm, especially for knee support during back squats. Knee sleeves are successful in providing frontal plane knee support during functional tasks, but have not been investigated in back squats. Knee wraps, a somewhat similar elastic material, provide elastic energy that increases weight lifted during back squats. Thus, it is possible the thick neoprene knee sleeves could prove advantageous for back squats. The purpose of this study was to examine the effects of knee sleeves on weight lifted, knee biomechanics, and muscle activations during back squats.Methods:Fifteen resistance trained men and women performed 1-repetition maximum (1-RM) squats to full depth and 80% 1-RM to full and parallel depths during two separate randomized sessions: with/without knee sleeves. Three-dimensional motion capture, force platforms, and electromyography recorded knee biomechanics and activations of the rectus femoris, vastus medialis, biceps femoris long head, and gluteus maximus during all squats.Results:Maximal weight lifted did not improve when using knee sleeves. Frontal plane knee biomechanics did not differ for 1-RM or submaximal squats to either depth between conditions. Knee external rotation moments during descent were larger with sleeves during submaximal squats. Reduced integrated ascent phase gluteus maximus activations occurred during both 1-RM and submaximal squats with knee sleeves.Conclusions:The results of this study show that wearing knee sleeves does not provide additive effects to weight lifted and do not appear to alter frontal plane mechanics during weighted back squats

The Effects of Elevation Gain on the Pack Hike Test: Implications for Interagency Hotshot Crews

It is unknown if administering a graded load carriage task, which more closely mirrors the occupational circumstances wildland firefighters are exposed to, improves the validity of the Pack Hike Test and its’ ability to differentiate between the fitness profiles amongst Interagency Hotshots (IHC) and type 2 crews. PURPOSE: The aim of the current study was to examine the performance differences and HR responses between IHC and type 2 crews when completing a maximal effort graded load carriage task. METHODS: This study compared performance outcome measures amongst two classes of hand crews, Type 1 (IHC; n=12) and Type 2 (T2C; n=7). All participants engaged in one maximal effort hike test, which covered 1.3 miles with a 16.5% grade while carrying a 45 lb. load carriage system. Additionally, participants were instructed to complete the hike at a maximal pace and were given no feedback or motivation during the execution of the test. Immediately following the termination of the test, participants were instructed to perform a supine 1-minute recovery period. Participants wore Polar H10 monitors in order to collect the following variables: Pace (min/mile), HR recovery (bpm), HR average (bpm) and HR max (bpm). RESULTS: There were no significant differences between groups for any of the performance or HR response variables (p\u3e.05). Compared to T2C, IHC pace (-2.07 min/mile) as well as HR recovery (+3.00 bpm) values trended towards increased performance. Additionally, a tendency emerged for IHC members to sustain higher physiological stress, as indicated by greater relative HR average (+8.18 bpm) and HR max (+8.51 bpm) values. CONCLUSION: IHC, compared to T2C, showed a slight positive trend in their ability to sustain maximal work rates for a longer duration, thus resulting in improved hiking performance. A maximal effort graded load carriage test may provide a better understanding of occupational fitness amongst wildland firefighters

Differences in Joint Kinematics and Electromyography Activity among the Conventional, Block, and Deficit Deadlifts

The conventional deadlift (CDL) is a commonly used lower-body exercise that utilizes the legs, hips, back, and trunk muscles. The block deadlift (BDL) and the deficit deadlift (DDL) are two variations that alter the starting position and height of a deadlift, however, there is a lack of literature that examines both. PURPOSE: To quantify and compare joint kinematics and peak muscle activation differences between a CDL, BDL, and DDL. METHODS: Twenty total resistance-trained male and female participants (25.1 ± 3.6 yrs old, 81.0 ± 15.2 kg) performed a one-repetition maximum (1RM) in the CDL on day one. At least 72 hours later, participants performed five repetitions for all three deadlift conditions (deadlift from the floor, 4” block, and 4” deficit) at 70% 1RM of their CDL. A one-way ANOVA was used to assess differences in initial sagittal joint angles and range of motion (ROM) of the ankle, knee, hip, and trunk during the concentric phase of the deadlifts. Muscle activity (peak electromyography) of the vastus lateralis (VL), gluteus maximus (GM), bicep femoris (BF), and the erector spinae (ES) muscles were also assessed. RESULTS: There were significant main effects in initial joint angles and ROM for the ankle, knee, hip, and trunk (p \u3c 0.001 which were all significantly greater in the DDL compared to the CDL and BDL. The same variables were also significantly greater in the CDL than in the BDL. There were significant main effects for the BF (p = 0.010), GM (p \u3c 0.001), and VL (p \u3c 0.001) but not ES (p = 0.371) between the deadlift variations. Peak activation of the BF in the DDL was significantly greater than in the BDL (p = 0.049). Peak activation of the GM was significantly greater in the DDL than in the CDL (p = 0.046) and BDL (p = 0.002). However, there was no significant difference in GM activation between the CDL and BDL. Peak activation of the VL was significantly greater in the DDL compared to both the CDL and BDL (p \u3c 0.001 for both). VL activation in the CDL was also significantly greater than the BDL (p \u3c 0.001). CONCLUSION: Both the BDL and the DDL can be implemented in training programs by athletes and coaches. Each variation can be used to elicit different muscle activation responses of either the BF, GM, or VL

Walking Biomechanics and Energetics of Individuals with a Visual Impairment: A Preliminary Report

Purpose. Although walking gait in sighted populations is well researched, few studies have investigated persons with visual impairments (VIs). Given the lack of physical activity in people with VIs, it is possible that reduced efficiency in walking could adversely affect activity. The purposes of this preliminary study were to (1) examine the biomechanics and energetics utilized during independent and guided walking in subjects with VIs, and (2) compare gait biomechanics between people with VIs and sighted controls. Methods. Three-dimensional motion capture and force platforms were used during independent and guided walking at self-selected speeds. Joint angles, moments, external work, and recovery were compared. Results. The VI group performed independent walking slower and with reduced stride lengths compared with guided walking and sighted controls. Hip range of motion and peak joint moments were reduced during independent walking in the VI group compared with guided walking and controls. Work was greater by 114%, 32%, and 16% in the VI group during independent than during guided walking. Recovery was 11% greater in guided vs. independent walking. Conclusions. In the presented preliminary study among 3 persons with congenital VIs, independent walking was a less efficient mode of walking compared with guided walking and that of sighted controls

Electromyographic Examination of Hip and Knee Extension Hex Bar Exercises Varied by Starting Knee and Torso Angles

International Journal of Exercise Science 15(1): 541-551, 2022. Variations of the deadlift can be executed using the hexagonal (hex) bar by altering, for instance, the knee and torso angles while maintaining a constant hip angle at the start position. PURPOSE: To examine muscle activation patterns of the biceps femoris, rectus femoris, and erector spinae during three deadlift variations using the hex bar. METHODS: Twenty resistance-trained male and female subjects performed hex bar deadlift variations in three different starting knee flexion positions: 128.4 ± 8.5°, 111.9 ± 8.7°, and 98.3 ± 6.5°. Subjects performed three repetitions at 75% of their three-repetition maximum. Electromyography sensors were placed on the dominant biceps femoris, rectus femoris, and lumbar erector spinae. A one-way repeated measures ANOVA was used to detect differences in mean and peak EMG values normalized to maximum voluntary isometric contraction (MVIC) (p \u3c 0.05). RESULTS: As knee flexion increased at the starting position, mean activation of the rectus femoris increased (24.7 ± 21.5 35.5 ± 25.4 62.1 ± 31.3% MVIC, p \u3c 0.001), while biceps femoris (40.6 ± 17.9 34.0 ± 16.4 28.1 ± 14.5% MVIC, p = 0.003) and erector spinae (73.0 ± 27.6 65.9 ± 34.4 54.9 ± 32.5% MVIC, p = 0.009) activation decreased. Peak activation of the rectus femoris increased (46.9 ± 33.0 60.9 ± 38.7 99.3 ± 41.6% MVIC, p \u3c 0.001) while decreasing in the erector spinae (118.6 ± 47.1 105.9 ± 49.4 89.1 ± 40.1% MVIC, p = 0.008). The rectus femoris experienced the greatest mean differences of the three muscles. CONCLUSIONS: Practitioners should consider the muscular goals when adjusting the starting position of a hex bar deadlift as posterior chain recruitment diminished and quadriceps activation increased as knee flexion increased

Pilot Study: The Effect of Weight Belts and Lifting Straps on Conventional Deadlift Performance

Weight belts and lifting straps are frequently worn when performing deadlifts for their ergogenic advantages, but no prior research has examined their effects. Purpose: The pilot study investigated the effects of weight belts and lifting straps on deadlift performance variables. Methods: One male subject participated (age 26 years, 78kg, 1.73M) in four separate days, performing conventional deadlifts (CDL) under varying conditions. On day one, the subject performed the CDL without weight belts and lifting straps (RAW). The remaining sessions were randomized between using a weight belt only (BO), lifting straps only (SO), or both weight belt and lifting straps (BaS). Each day, the subject worked up to a one-repetition maximum (1-RM), followed by a set of as many repetitions as possible (AMRAP) at 90% and then 70% of his 1-RM. Variables recorded was peak and mean vertical ground reaction forces (VGRF) with each foot standing on Bertec force plates, 1-RM, recorded the repetitions at 90% and 70% AMRAP, and rate of force displacement (RFD). Results: 1-RM was greatest in SO (193.2kg), followed by BaS (190.9kg), BO (138.6kg), and RAW (138.6kg). Repetitions at 90% AMRAP were greatest in BO (7 repetitions), followed by RAW (5 repetitions), BaS (4 repetitions), and SO (1 repetition). At 70% AMRAP, repetitions were greatest in both RAW (13 repetitions) and BO (13 repetitions), followed by BaS (11 repetitions), and SO (10 repetitions). Peak VGRF were greatest in SO (1,521.18N), followed by BaS (1,368.68N), BO (1,254.76N), and RAW (1,133.26N). Mean VGRF were greatest in SO (1,345.97N), followed by BaS (1,239.17N), BO (1,145.31N), and RAW (1,024.99N). RFD were greatest in BO (836.50N/s), followed by RAW (781.55N/s), SO (446.31N/s), and BaS (424.39N/s). Conclusion: These pilot data indicate that weight belts and lifting straps improved 1-RM, AMRAP, VGRF, and RFD performance, but further studies with larger, more diverse samples are needed to validate these findings

Comparing Knee Kinetics and Muscular Activity between the Barbell Squat and Flywheel Squat in Recreationally Trained Females

Previous literature has supported flywheel (FW) training with inducing muscular size and strength comparable to resistance training with free weights. However, it remains unclear how the biomechanical demands of these two training methods differ regarding reducing the risk of load-dependent injuries. PURPOSE: With the growing population of female astronauts, this study aimed to compare knee joint kinetics and muscle activation when squatting to full depth on the barbell back (BB) squat and a gravity-independent FW device utilizing technology to be deployed in future long-term space missions. METHODS: Twenty recreationally trained females (22.3 ± 2.7 yrs, 1.6 ± 0.1 m, 59.8 ± 6.8 kg) with at least two years of experience in BB squat training participated in this study. The first session involved one-repetition maximum (1RM) testing on the BB squat and familiarizing the participants with squatting on the FW device (YoYo ™ Multigym). In session two, the participants conducted: 1) one set of seven repetitions at 83% of their 1 RM in the BB and 2) one set of seven maximal repetitions on the FW training device using an inertial load of 0.100 kg ⋅ m2. The order of the exercises in session two was randomized. Three-dimensional motion capture, force platforms, and electromyography assessed knee joint moments and muscle activation on the participants\u27 dominant limb. Paired t-tests were conducted to compare these variables, with a significance set at p ≤ 0.05. RESULTS: Analysis revealed peak knee extensor moments were greater in the BB squat (BB: 2.14 ± 0.36 Nm/kg, p = 0.004; FW: 1.94 ± 0.06 Nm/kg). The BB squat elicited greater mean muscle activity over the set compared to FW squats in the following: (vastus lateralis: +5.68%, p = 0.015; bicep femoris: +4.63%, p \u3c 0.001; gluteus maximus: +4.67%, p = 0.024; gluteus medius: +2.75%, p = 0.011; gastrocnemius lateralis: +3.09%, p = 0.028; gastrocnemius medius: +2.48%, p = 0.024). However, FW squats attained greater tibialis anterior activity (+5.56%, p = 0.04). There was no significant difference in muscle activity observed in the rectus femoris and vastus medialis. CONCLUSION: Although FW training requires less mechanical demand on the knee extensors when squatting to similar depths, participants achieved greater muscular activation during the BB squat

Footwear Affects Conventional and Sumo Deadlift Performance

Barefoot weightlifting has become a popular training modality in recent years due to anecdotal suggestions of improved performance. However, research to support these anecdotal claims is limited. Therefore, the purpose of this study was to assess the differences between the conventional deadlift (CD) and the sumo deadlift (SD) in barefoot and shod conditions. On day one, one-repetition maximums (1 RM) were assessed for thirty subjects in both the CD and SD styles. At least 72 h later, subjects returned to perform five repetitions in four different conditions (barefoot and shod for both CD and SD) at 70% 1 RM. A 2 X 2 (footwear x lifting style) MANOVA was used to assess differences between peak vertical ground reaction force (VGRF), total mechanical work (WORK), barbell vertical displacement (DISP), peak vertical velocity (PV) and lift time (TIME) during the concentric phase. The CD displayed significant increases in VGRF, DISP, WORK, and TIME over the SD. The shod condition displayed increased WORK, DISP, and TIME compared to the barefoot condition. This study suggests that lifting barefoot does not improve performance as no differences in VGRF or PV were evident. The presence of a shoe does appear to increase the DISP and WORK required to complete the lift, suggesting an increased work load is present while wearing shoes