diff --git a/back_end/src/main/java/hackathon/FrisbYEE/rest/SessionResource.java b/back_end/src/main/java/hackathon/FrisbYEE/rest/SessionResource.java
index e25b2d5..5ec326f 100644
--- a/back_end/src/main/java/hackathon/FrisbYEE/rest/SessionResource.java
+++ b/back_end/src/main/java/hackathon/FrisbYEE/rest/SessionResource.java
@@ -116,17 +116,23 @@ public class SessionResource {
 
     //Commented because not finished
 
-    /*@GetMapping("/activities/add")
+    @GetMapping("/{id_session}/activities/add/{id_act}")
     @PreAuthorize("hasRole('coach') or hasRole('admin')")
-    public ResponseEntity<?> addActivity(@RequestBody ActiviteDTO dto) {
-        try {
-            Activite activite = maptoEntity(dto);
-            activiteDAO.save(activite);
-            return ResponseEntity.status(HttpStatus.CREATED).body(maptoDTO(activite));
-        } catch (Exception ex) {
-            return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(ex.getMessage());
+    public ResponseEntity<?> addActivity(@PathVariable Integer id_sess, @PathVariable Integer id_act) {
+        Session s = sessionDAO.findById(id_sess).get();
+        if(s.equals(null)){
+            return ResponseEntity.status(HttpStatus.NOT_FOUND).body("Session not found");
         }
-    }*/
+        Activite a = activiteDAO.findById(id_act).get();
+        if(a.equals(null)){
+            return ResponseEntity.status(HttpStatus.NOT_FOUND).body("Activite not found");
+        }
+        List<Activite> l = s.getActivites();
+        l.add(a);
+        s.setActivites(l);
+        sessionDAO.save(s);
+        return ResponseEntity.status(200).body(maptoDTO(s));
+    }
 
     private SessionDTO maptoDTO(Session s) {
         SessionDTO dto = new SessionDTO();
diff --git a/front_end/src/api.ts b/front_end/src/api.ts
index da90390..cf5a953 100644
--- a/front_end/src/api.ts
+++ b/front_end/src/api.ts
@@ -50,6 +50,7 @@ export const athleteService = {
     getActivitiesForSession: (sessionId: number | string) => api.get(`/athletes/session/${sessionId}/activities`),
     getSessionsAfterDate: (athleteId: number | string, date: string) => api.get(`/athletes/${athleteId}/session/after/${encodeURIComponent(date)}`),
     getSessionsBetweenDates: (athleteId: number | string, startDate: string, endDate: string) => api.get(`/athletes/${athleteId}/session/between/${encodeURIComponent(startDate)}/${encodeURIComponent(endDate)}`),
+    addActivity: (id_sess: number, id_act: number) => api.get(`/${id_sess}/activities/add/${id_act}`)
 };
 
 export const activiteService = {