diff --git a/pkg/training/repository.go b/pkg/training/repository.go
index 642b8a3..2e4fce0 100644
--- a/pkg/training/repository.go
+++ b/pkg/training/repository.go
@@ -1,6 +1,8 @@
 package training
 
 import (
+	"sync"
+
 	"github.com/shopspring/decimal"
 	"gitlab.mareshq.com/hq/yggdrasil/internal/currency"
 )
@@ -15,6 +17,7 @@ type TrainingRepository interface {
 
 type InMemoryTrainingRepository struct {
 	trainings map[TrainingID]Training
+	lock      sync.RWMutex
 }
 
 func NewInMemoryTrainingRepository() *InMemoryTrainingRepository {
@@ -189,12 +192,18 @@ func NewInMemoryTrainingRepository() *InMemoryTrainingRepository {
 }
 
 func (r *InMemoryTrainingRepository) Create(training *Training) error {
+	r.lock.Lock()
+	defer r.lock.Unlock()
+
 	training.ID = NewTrainingID()
 	r.trainings[training.ID] = *training
 	return nil
 }
 
 func (r *InMemoryTrainingRepository) FindByID(id TrainingID) (*Training, error) {
+	r.lock.RLock()
+	defer r.lock.RUnlock()
+
 	training, ok := r.trainings[id]
 	if !ok {
 		return nil, ErrTrainingNotFound
@@ -203,6 +212,8 @@ func (r *InMemoryTrainingRepository) FindByID(id TrainingID) (*Training, error)
 }
 
 func (r *InMemoryTrainingRepository) FindAll() ([]Training, error) {
+	r.lock.RLock()
+	defer r.lock.RUnlock()
 
 	trainings := make([]Training, 0, len(r.trainings))
 	for _, training := range r.trainings {
@@ -212,11 +223,17 @@ func (r *InMemoryTrainingRepository) FindAll() ([]Training, error) {
 }
 
 func (r *InMemoryTrainingRepository) Update(training *Training) error {
+	r.lock.Lock()
+	defer r.lock.Unlock()
+
 	r.trainings[training.ID] = *training
 	return nil
 }
 
 func (r *InMemoryTrainingRepository) Delete(id TrainingID) error {
+	r.lock.Lock()
+	defer r.lock.Unlock()
+
 	_, ok := r.trainings[id]
 	if !ok {
 		return ErrTrainingNotFound