Validity and Reliability of a New Inertial Device for Monitoring Range of Motion at the Pelvis during Sexual Intercourse

Abstract

To understand the physical demands of sexual intercourse, it is necessary to monitor the kinematic parameters of this activity using relatively non-invasive technology. The aims of this study are to analyze the validity and reliability of an inertial device for monitoring the range of motion at the pelvis during simulated intercourse and compare the range of motion (ROM). Twenty-six adults were monitored during intercourse using an inertial device (WIMU) and a motion capture system (gold standard) in a test that consisted of 4 sets of 20 simulated in–out cycles (IOC) in missionary and cowgirl positions. Men and women were tested separately in a laboratory setting for simulated intercourse aims. There were no differences between the WIMU and the gold standard system at fast pace (p > 0.05), whereas there were differences at slow pace (~2.04°; p ≤ 0.05; d = 0.17). Intraclass correlation coefficients (ICCs) for the relationship between systems was very close to 1 at both paces (slow: 0.981; fast: 0.998). The test–retest reliability analysis did not show any difference between sets of measurements. In conclusion, WIMU could be considered as a valid and reliable device for IOC range of motion monitoring during sexual intercourse in missionary and cowgirl positions.

Effect of Playing Position, Match Half, and Match Day on the Trunk Inclination, G-Forces, and Locomotor Efficiency Experienced by Elite Soccer Players in Match Play

“…Although the tracking systems used in this study have been considered as valid, reliable and suitable instruments to measure position-related variables [ 42 , 43 ] and trunk inclination in the sagittal plane [ 30 ], the gold standard technology for measuring position and orientation of human body segments are optical tracking systems [ 30 , 44 , 45 ]. However, the use of optical tracking systems is limited to laboratory settings for technical reasons [ 30 , 44 , 45 ] and thus, tracking systems with inertial sensors and GPS technology have vast implications for human activity monitoring. In consequence, future investigations analyzing the trunk kinematics and postural demands should consider the advantages of using these wearable sensors as well as their validity and reliability for measuring each parameter.…”

“…The “ATTITUDE EULER Z” was used to analyze the sagittal trunk inclination (in degrees) [ 30 ] ( Figure 3 A). Since the upright posture equals 0° and the original data collected by the unit reported 90° for the same position, the researchers applied a simple formula, which was the data value from “ATTITUDE EULER Z” plus 90, to obtain the right position ( Figure 3 B).…”

Kinematic Analysis of the Postural Demands in Professional Soccer Match Play Using Inertial Measurement Units

“…Since each player wore a WIMU Pro device, which was vertically placed in the back pocket of a chest vest, the “ATTITUDE EULER Z” represented the orientation of the device (in degrees) for movements within the z -axis (i.e., trunk flexion and extension movements) [ 19 ]. This device has been considered as a reliable instrument for measuring the inclination for movements within the z -axis (mean bias: ~1.2°; intraclass correlation coefficients >0.97; coefficient of variation <7%) [ 19 ]. Then, these data, which were collected at 100 Hz, were used to calculate the trunk inclination zones based on a recent protocol [ 4 ].…”

“…Nevertheless, more studies on the postural demands of professional soccer players during match play are necessary, because it is the only study published to date [ 17 ]. Perhaps one of the reasons for the lack of research on this topic is explained by the methodological difficulties associated with the instruments used for measuring trunk kinematics [ 19 ]. Although the gold standard instruments for this aim are the motion capture systems, these are limited to laboratory settings [ 19 , 20 ].…”

“…Perhaps one of the reasons for the lack of research on this topic is explained by the methodological difficulties associated with the instruments used for measuring trunk kinematics [ 19 ]. Although the gold standard instruments for this aim are the motion capture systems, these are limited to laboratory settings [ 19 , 20 ]. In recent years, wearable inertial measurement units have been considered as alternative instruments for motion capture, since these may give insight into how soccer players use their trunk to perform the sport-specific skills in match play [ 4 , 21 ].…”