Effects of a band loop on muscle activity and dynamic Knee valgus during pedaling

Highlights

• Pedaling with the band can be an effective method to control Dynamic Knee Valgus.

• The band can increase the Gmed activity and Gmed/TFL ratio in its optimal length.

• Increasing the workload during pedaling with the band must be done with caution.

Abstract

Background

Change in the lower extremity alignments in the frontal plane and muscle activation patterns have been associated with lower extremity injuries. Therefore, to prevent injuries, many therapeutic protocols focus on find ways to correct dynamic knee valgus (DKV).

Methods

Thirty-one recreational male cyclists with DKV (26.4 ± 4.5 years, 176.63 ± 7.51 cm, 75.81 ± 9.29 kg, 23.20 ± 4.15 kg/m2) volunteered to participate in this study. Simultaneous recordings of kinematic and electromyography data were performed on ten consecutive pedal cycles which began during the last 30 seconds of each four test condition: with band at 0.5 kg workload, with band at 2 kg workload, without band at 0.5 kg workload, and without band at 2 kg workload. The paired t-test was used for statistical analysis (p < 0.05).

Results

The results indicated significant differences in VM (band = 0.029, no band = 0.031) and VL (band = 0.015, no band = 0.035) activation between workloads in each condition. Also there were significant differences in Gmed activation (0.5kg = 0.001, 2kg = 0.037), onset of Gmed (0.5kg = 0.048, 2kg = 0.012), offset of Gmed (0.5kg = 0.048, 2kg = 0.015), TFL activation (0.5kg = 0.001, 2kg = 0.041) and offset of TFL (0.5kg = 0.078, 2kg = 0.005) between the band and no band conditions. There was no different significant in VM/VL ratio between in each of four testing conditions (p > 0.05). The Gmed/TFL ratio was significantly greater in band condition than no band at both 0.5 (p = 0.045) and 2 kg (p = 0.001) workload. Knee abduction angle was affected by the band loop during the pedaling at two different workloads (0.5 kg: p = 0.047, 2 kg: p = 0.021) but mean (p = 0.027) and peak (p = 0.033) knee abduction angle significantly increased with increasing workload during the pedaling with band loop.

Conclusions

pedaling with the band loop can be considered as an effective method to increase the Gmed, Gmed/TFL ratio and control of DKV but increasing the workload during pedaling must be done with caution to prevent DKV.

Introduction

Cycling is a popular recreational activity that can provide health benefits and improve cardiovascular fitness [1]. Compared to hiking or running, cycling allows people to work on muscle strength and lower extremity mobility while avoiding heavy loading to the joint, and in other words, cycling has the benefit of reducing knee joint loads compared to walking, so it is often prescribed as a rehabilitation exercise by many health professionals [2]. Knee pain has been reported in between 40–60 % of recreational cyclists [3]. Iliotibial band syndrome (ITBS) and Patella Femoral Pain Syndrome (PFPS) in the knee are usually one of the most common sports injuries that are associated with overuse injuries in endurance runners, professional cyclists, and recreational cyclists [4,5]. ITBS occurs due to iliotibial band friction during knee flexion and extension on the external epicondyle during exercise. This syndrome in cycling is usually caused by increased tibia internal rotation during pedaling, have a tight ITB, position of the foot on the pedal so that the fingers are inwardly inclined, increased hip flexion, excessive bicycle seat height [[5], [6], [7]]. In this regard reported Excessive dynamic knee valgus (DKV) during dynamic activities has been linked with the development of lower extremity injuries such as PFPS and ITBS [8,9]. DKV is an abnormality of neuromuscular control over the lower limb that a 10 % increase in the q-angle increased the stress on the patellofemoral joint by 45 % [10]. In this regards, Studies have demonstrated that patients with PFPS present greater DKV than do controls without PFPS [11,12]. On the other hand, researchers have shown that muscle imbalance and changes in muscle activity pattern are also associated with PFPS and ITBS [13,14]. According to Selkowitz et al. (2012), increased tensor fasciae latae (TFL) muscle activity over the gluteus medius (Gmed) muscle can exert external force by connecting the iliotibial band to the patella, which is associated with PFPS and ITBS [15]. Also, poor patellar tracking due to the unbalanced activation of the vastus medialis (VM) and vastus lateralis (VL) muscles has been considered to contribute to PFP [16].

In this regards, it has been suggested that Gmed activity as a muscle controlling the adduction and internal rotation of the hip is a key mechanism in preventing DKV [15]. Therefore, exercise strategies that increase Gmed activity during cycling may reduce DKV. Various equipment and tools have been designed to be used in training programs that require complex movements, which are very popular among trainers and corrections specialists. They use this tool to correct faster and more effective motor dysfunctions in athletes and patients. One of these tools is a band loop, which researchers have used in a variety of fields with training and rehabilitation goals in different fields [17]. Although Gooyers et al. in their study hypothesized that band loop at the end of the femur may encourage practitioners to control hip internal rotation and thus prevent DKV during exercise [18]; But Hewett et al. reported in a study that the band loop did not effect on DKV correction during squat [19]. However, other authors acknowledged that the results may vary across exercises and contexts [17]. In the present study, we first hypothesize that cycling with band loop can increase Gmed muscle activation. This will ultimately affect the kinematic state of the knee while cycling and also by increasing the Gmed / TFL activation ratio reduces external tracking to the patella and prevents PFP and ITBS injuries. Therefore, according to the aforementioned, considering the kinematics and pattern of activity of the muscles around the lower limb joints and especially the knee while pedaling with and without the band loop can provide useful information for designing appropriate exercise for corrections specialists and therapists to Prevention of injury, especially in subjects with DKV.