diff --git a/kafka-connect-fitbit-source/src/main/java/org/radarbase/connect/rest/fitbit/converter/FitbitIntradayHeartRateAvroConverter.java b/kafka-connect-fitbit-source/src/main/java/org/radarbase/connect/rest/fitbit/converter/FitbitIntradayHeartRateAvroConverter.java
index 89bc4cf1..92fb75e5 100644
--- a/kafka-connect-fitbit-source/src/main/java/org/radarbase/connect/rest/fitbit/converter/FitbitIntradayHeartRateAvroConverter.java
+++ b/kafka-connect-fitbit-source/src/main/java/org/radarbase/connect/rest/fitbit/converter/FitbitIntradayHeartRateAvroConverter.java
@@ -64,12 +64,18 @@ protected Stream<TopicData> processRecords(
 
     // Used as the date to convert the local times in the dataset to absolute times.
     ZonedDateTime startDate = request.getDateRange().start();
+    Instant rangeStart = startDate.toInstant();
+    Instant rangeEnd = request.getDateRange().end().toInstant();
 
     return iterableToStream(dataset)
         .map(tryOrNull(activity -> {
           Instant time = startDate.with(LocalTime.parse(activity.get("time").asText()))
               .toInstant();
 
+          if (time.isBefore(rangeStart) || !time.isBefore(rangeEnd)) {
+            return null;
+          }
+
           FitbitIntradayHeartRate heartRate = new FitbitIntradayHeartRate(
               time.toEpochMilli() / 1000d,
               timeReceived,
diff --git a/kafka-connect-fitbit-source/src/main/java/org/radarbase/connect/rest/fitbit/route/FitbitIntradayHeartRateRoute.java b/kafka-connect-fitbit-source/src/main/java/org/radarbase/connect/rest/fitbit/route/FitbitIntradayHeartRateRoute.java
index f7f06644..471056f8 100644
--- a/kafka-connect-fitbit-source/src/main/java/org/radarbase/connect/rest/fitbit/route/FitbitIntradayHeartRateRoute.java
+++ b/kafka-connect-fitbit-source/src/main/java/org/radarbase/connect/rest/fitbit/route/FitbitIntradayHeartRateRoute.java
@@ -17,16 +17,20 @@
 
 package org.radarbase.connect.rest.fitbit.route;
 
-import static java.time.format.DateTimeFormatter.ISO_LOCAL_TIME;
-import static java.time.temporal.ChronoUnit.SECONDS;
+import static java.time.ZoneOffset.UTC;
 
 import io.confluent.connect.avro.AvroData;
+
+import java.time.Instant;
+import java.time.temporal.ChronoUnit;
+import java.util.List;
 import java.util.stream.Stream;
 import org.radarbase.connect.rest.fitbit.converter.FitbitIntradayHeartRateAvroConverter;
 import org.radarbase.connect.rest.fitbit.request.FitbitRequestGenerator;
 import org.radarbase.connect.rest.fitbit.request.FitbitRestRequest;
 import org.radarbase.connect.rest.fitbit.user.User;
 import org.radarbase.connect.rest.fitbit.user.UserRepository;
+import org.radarbase.connect.rest.fitbit.util.DateRange;
 
 public class FitbitIntradayHeartRateRoute extends FitbitPollingRoute {
   private final FitbitIntradayHeartRateAvroConverter converter;
@@ -39,15 +43,22 @@ public FitbitIntradayHeartRateRoute(FitbitRequestGenerator generator,
 
   @Override
   protected String getUrlFormat(String baseUrl) {
-    return baseUrl + "/1/user/%s/activities/heart/date/%s/1d/1sec/time/%s/%s.json?timezone=UTC";
+    // URL format args: user-id, date
+    return baseUrl + "/1/user/%s/activities/heart/date/%s/1d/1sec.json?timezone=UTC";
   }
 
   protected Stream<FitbitRestRequest> createRequests(User user) {
-    return startDateGenerator(getOffset(user).plus(ONE_SECOND).truncatedTo(SECONDS))
+    // Important: heart rate is queried at the resolution of a single
+    // day, so the offset for the next request will be set to the next day.
+    Instant startDate = this.getOffset(user).plus(ONE_DAY)
+        .atZone(UTC)
+        .truncatedTo(ChronoUnit.DAYS).toInstant();
+    List<DateRange> dateRangeStream = startDateGenerator(startDate).toList();
+    return dateRangeStream.stream()
         .map(dateRange -> newRequest(user, dateRange,
-            user.getExternalUserId(), DATE_FORMAT.format(dateRange.start()),
-            ISO_LOCAL_TIME.format(dateRange.start()),
-            ISO_LOCAL_TIME.format(dateRange.end().truncatedTo(SECONDS))));
+            user.getExternalUserId(),
+            DATE_FORMAT.format(dateRange.start())
+        ));
   }
 
   @Override