It’s not working because of TableRow inside RadioGroup. All RadioButtons are not grouped together because of TableRow between them.
RadioButton should be the direct child of RadioGroup, Otherwise grouping does not work.
Just change your code like this it will work :
<RadioGroup
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/RGroup">
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Abdominal"
android:id="@+id/Abdominal"/>
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Arm"
android:id="@+id/Arm"/>
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Back"
android:id="@+id/Back" />
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Chest"
android:id="@+id/Chest"/>
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Leg"
android:id="@+id/Leg"/>
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Shoulder"
android:id="@+id/Shoulder"/>
</RadioGroup>
Hope this helps. 🙂